J Clin Pathol: first published as 10.1136/jcp.31.Suppl_12.223 on 1 January 1978. Downloaded from

J. clin. Path., 31, Suppl. (Roy. Coll. Path.), 12, 223-238

A consensus Diseases of : a consensus

D. L. GARDNER From the Department ofHistopathology, University of Manchester

The accelerated rate of acquisition of new teoglycans that chondrocytes (see R. A. Stockwell chemical, biological, physical, and mechanical (Stockwell, 1978) at page 7) differ most obviously knowledge of the connective tissues may obscure from fibroblasts. Chondrocytes synthesise and export pathological aspects of connective tissue diseases much and sometimes elastic material; but rather than clarify their nature. To guard against the cytological recognition of chondrocyte-rich this possibility periodic, critical reviews of analytical tissues such as hyaline articular cartilage is most and experimental advances are salutary. They readily affected by identifying the abundant, pro- provide an opportunity not only to assess recent teoglycan-containing matrix. Thus a chondrocyte investigations but also to compare the widely can be said to be a connective tissue in which the differing problems encountered in connective tissue formation of a proteoglycan-rich matrix dominates diseases in different parts of the world. They also all other activities. Although this over-simplification offer an opportunity to reclassify connective tissue can be misleading, it gives an important guide to the disease in the light of new understanding. manner in which diseases of chondrocytes such as chondrodystrophia fetalis, the chondrodystrophies, Summary of new knowledge and the neoplasms of cartilagenous tissues are copyright. manifested clinically. Much of our information relates to the biology, Honor Fell (Fell, 1978; see page 14) reminds us of biochemistry, physics, and mechanics of the con- the distinctive properties of synoviocytes. For nective tissues; much less concerns the precise pathologists the two most interesting characteristics manner in which these tissues are injured or dis- of synoviocytes are their voracious capacity for turbed in the wide range of disorders included in this phagocytosis and their preoccupation with the review. The fibroblast (see M. Abercrombie synthesis of hyaluronic acid. However, pathologists (Abercrombie, 1978) at page 1)-ubiquitous, often remark on the neoplasm-like proliferation of

resilient, and versatile-is the prototype on which these cells and note that metastatic carcinomatosis http://jcp.bmj.com/ much of our present understanding of connective of the synovial tissue is curiously rare (or seldom tissue is based. Identified in tissue culture recognised). partly by shape, partly by spatial relationships to Contractility could be said to be a fundamental other cells, the cell is contractile and motile. Much property of all cells. It is not a feature of the hyaline of its resources is devoted to producing the contrac- cartilagenous chondrocyte, trapped like a crustacean tile that permit the active, slow directional in a chondroitin sulphate-rich gel of its own origin, movement that ceases when cell-to-cell contact but the same cells may move in monolayer culture inhibits movement. Ready multiplication depends when freed from this constraint and from contact on October 2, 2021 by guest. Protected on cell density and on the local concentration of inhibition. Nevertheless, it is in the muscle cell components in the culture medium. However, the (see J. C. Sloper, M. C. Barrett, and T. A. Partridge limitation of replicative cycles to 60 or so, the (Sloper et al., 1978) at page 25) that we find con- Hayflick effect, may be an artefact of culture caused tractility refined to its biological limit to provide by the elimination of a class of stem cells able to locomotion in the multi-cellular parent organism, perpetuate multiplication indefinitely in vivo. and diseases of muscle most often appear as dis- An essential function of the fibroblast, and one turbances of contractility. central to our understanding of the diseases of The principal exports of the connective tissue cells connective tissue, is the manufacture and export of are collagen (see D. S. Jackson (Jackson, 1978) at structural and enzymic proteins, of collagen and page 44, and A. J. Bailey (Bailey, 1978) at page 49) elastin, and of the proteoglycans. It is in the pro- elastin (Bailey, 1978) (and presumably elastic micro- portion of energy given to producing the pro- fibrillar glycoprotein), and the proteoglycans (see 223 J Clin Pathol: first published as 10.1136/jcp.31.Suppl_12.223 on 1 January 1978. Downloaded from

224 D. L. Gardner H. Muir (Muir, 1978) at page 67). To the pathologist spondylitis and the evidence implicating the HLA the advances in understanding of the mechanisms of antigens in the origin of these diseases (Brewerton synthesis, export, maturation, and metabolism of et al., 1973; see D. A. Brewerton (Brewerton, 1978) these materials are crucial: the new knowledge at page 117) have been under intensive study in permits logical identification and classification of experiments that move more and more towards disease and the sensible and purposeful planning an indictment of microbiological agents such as of experiments undertaken to examine pathogenesis Klebsiella pneumoniae as initiating factors (Ebringer and natural history. This logic has led Lapiere and et al., 1978). However, there is not yet any conclusive Nusgens (1976) and Levene (see C. I. Levene (Levene, evidence that rheumatoid arthritis is provoked by 1978a) at page 82) to the reclassification of many of any known infective agent, despite striking pointers the connective tissue diseases on the basis of inherited towards the role of mycoplasmas (Taylor-Robinson or environmental disorders of collagen production and Taylor, 1976), diphtheroids (Duthie et al., 1976), and maturation (see F. M. Pope and A. C. and viruses (Marmion, 1976; Hart and Marmion, Nicholls (Pope and Nicholls, 1978) at page 95). 1977). Probably any putative infective agent would Similarly, the systematic identification of enzy- act by indirect, immunological mechanisms to cause mic defects in the inherited mucopolysaccharidoses and perpetuate tissue injury. A. M. Denman (Den- (McKusick, 1972), the glycosaminoglycan-storage man, 1978; see page 132) advances good circumstan- diseases, has promoted rational classification of tial evidence to show that at least five such mechan- these uncommon disorders. In turn, this has led to isms are possible. Very good reasons exist for important success in correcting inherited deficiencies suggesting that a C-type RNA virus operates in the by the transplantation offibroblasts to children born case of systemic lupus erythematosus, at least in the with deficiencies of the needed for normal heritable dog model of the disorder (Lewis and glycosaminoglycan degradation (see M. F. Dean Schwartz, 1976). That such an antigen can act (Dean, 1978) at page 120). Compared with the globally to alter or impair the immunological extent to which understanding of collagen and, to a mechanism-leading to the production of many lesser extent, elastin has advanced progress in abnormal antibodies, often of autoimmune character unravelling the problems of the basal lamina (see E. J. Holborow (Holborow, 1978) at page 144) copyright. (basement membrane) has been limited (see J. T. -seems beyond dispute. It remains of crucial im- Ireland (Ireland, 1978) at page 59). However, the portance to obtain evidence of a similar or presence in basal laminae of type IV collagen analogous mechanism in rheumatoid arthritis, and (Kefalides, 1974) and an appreciation of the role of there is some reason to believe that this evidence the basal laminae in controlling processes such as is forthcoming (Panayi, 1976). glomerular capillary filtration suggest that within the Recent discussions (Jayson, 1977) emphasise our next decade the detailed composition and physio- better appreciation of the nature of the process of logical role ofthis structure will be better understood, fibrosis, so important in determining the clinical

to the great benefit of pathologists. Thus the sel- behaviour and natural history of synovitis in http://jcp.bmj.com/ ective identification of type IV collagen in tissue rheumatoid arthritis; of cardiac valve disease in sections by the histochemical method of Bock (1978), rheumatic fever; of oesophageal, cardiac, and a technique based on the relatively high cystine dermal disorders in systemic sclerosis; and of the content of type IV collagen (8 half-cystine residues/ destructive and occlusive lesions in hepatic fibrosis 1000) compared with type III (2 half-cystine residues (see J. O'D. McGee and A. Fallon (McGee and /1000) and types I and II (from which cystine is Fallon, 1978) at page 150) and atherosclerosis (see absent), suggests that understanding of basal laminar C. I. Levene (Levene, 1978b) at page 165). The disease may advance quickly. origins of the lung lesions in the pneumoconioses on October 2, 2021 by guest. Protected Advances in enzymology in relation to the patho- (see P. C. Elmes and J. C. Wagner (Elmes and genesis of connective tissue disease have not been Wagner, 1978) at page 158) and the characteristic limited to analyses of lysosomal function (see pulmonary changes that develop in response to a L. Bitensky (Bitensky, 1978) at page 105), although wide variety of lung-injuring chemicals, physical it could fairly be claimed that the lysosomal concept agents, dusts, aerosols, and foreign antigens have (de Duve et al., 1955) was the spark that ignited the suggested ways in which the connective tissues can be present explosive advance in knowledge of the injured. Similarly, the demonstration (McGee and cathepsins in inflammation (Dingle, 1969) and, in Fallon, 1978) that excess collagen formation in particular, of the neutral collagenases in rheumatoid hepatic fibrosis can result from proline hydroxylase arthritis (Woolley et al., 1977, 1978). Concurrently, activity emphasises how analogous changes may the genetic basis for such common forms of poly- explain the chronic inflammation and- the fibrosis of arthritis as rheumatoid arthritis and ankylosing rheumatoid synovitis, ankylosing spondylitis (see J Clin Pathol: first published as 10.1136/jcp.31.Suppl_12.223 on 1 January 1978. Downloaded from

Diseases of connective tissue: a consensus 225 J. Ball (Ball, 1978) at page 200), and other inflam- It is hardly possible to consider a single disease of matory disorders of the connective tissues. the connective tissue system without immediately In the case of osteoarthrosis (see S. Y. Ali (Ali, realising the great gaps in our understanding. For 1978) at page 191) argument still rages on the nature example, advances in the therapy and prophylaxis of the first alteration in joint function and in hyaline of gout have been so spectacular that we are in- articular cartilage structure and composition that clined to overlook our ignorance of the ways in may precede the clinical disease (Gardner et al., which selected connective tissue foci come to act as 1978). It is certainly possible (Ali, 1978) that altered niduses for aggregates of monosodium urate dihyd- calcium hydroxyapatite metabolism can promote rate crystals (Scott, 1978). The discovery of an cartilage injury; the analogy with the accumulation association between the HLA antigens and diseases in cartilage of the calcium pyrophosphate of chon- such as ankylosing spondylitis only emphasises the drocalcinosis is very close (see P. Dieppe (Dieppe, fact that we are still wholly ignorant of the ways in 1978) at page 214). However, it seems to many that which selected connective tissues such as the synovial the progressive lesions of selected areas of hyaline and fibrocartilagenous joints, and the entheses, cartilage are distinct from the non-progressive become sites for sustained inflammation. The role alterations that deform hip joints examined at of microbiological agents in provoking focal necropsy (Byers et al., 1970). It certainly seems inflammation via hypersensitivity mechanisms is difficult to account for focal lesions by a metabolic suspected but wholly unproved. The reasons why the mechanism that could be held to predispose to aortic valve and the uveal tract are implicated are generalised calcium hydroxyapatite deposition in entirely obscure. In much the same way, progress load-bearing cartilage. Comparable difficulties attend in unravelling the pathogenesis of osteoarthrosis has our present views on gout (see J. T. Scott (Scott, failed to keep pace with dramatic advances in the 1978) at page 205). Here the problem is to account techniques of arthroplasty. It remains probable that for the selective deposition of urate in only very the term primary osteoarthrosis conceals the limited connective tissue sites in the face of high existence of a cluster of disorders, all terminating

plasma concentrations of urate that raise the with similar clinical signs and symptoms. copyright. extracellular fluid urate concentration in almost all In this account I have chosen to review some parts of the body. unanswered questions that relate respectively to Behind these metabolic changes, probably in- osteoarthrosis, rheumatoid arthritis, and the con- dependent of, although associated with, altered nective tissue neoplasms. Firstly (in relation to immunological responsiveness, lie the connective osteoarthrosis), do we properly understand the tissue phenomena that we attribute to ageing surface structure of articular cartilage? Secondly (in (Schofield and Weightman, 1978). Distinct from relation to rheumatoid arthritis), do we have a connective tissue alterations in growth and matu- proper model with which to undertake experi- ration, age changes are now believed to be subtle, mental laboratory studies? Thirdly (in relation to widespread, and multifactorial. In some circum- primary and metastatic neoplasms of the synovia), http://jcp.bmj.com/ stances altered immunological reactivity and age may is there a proper appreciation of the neoplastic both contribute to the accumulation of the AA diseases of connective tissue and of the apparent ofamyloidosis, an accumulation that reminds immunity of the synovial tissues to neoplasia? us ofthe genetic background ofsome rareforms ofthis curious disorder (see J. R. Hobbs (Hobbs, 1978) at WHAT IS THE TRUE NATURE OF HYALINE page 128). However, to attribute to the molecular ARTICULAR CARTILAGE SURFACES? anomalies of ageing any particular connective tissue disease such as osteoarthrosis or intervertebral An articulating Cartilage is an elastic Substance uniformly on October 2, 2021 by guest. Protected disc disorder (Ball, 1978) remains as much beyond compact, of a white Colour, and somewhat diaphanous, our present state of understanding as does the having a smoothpolishedSurface covered with a Membrane; explanation of most cases of amyloidosis. harder and more brittle than a Ligament, softer and more pliable than a (William Hunter, 1743). Ignorance of the connective tissue diseases Analytical microscopy of hyaline articular cartilage The imaginative Encyclopedia of Ignorance (1977) surfaces is dominated by the salutary chemical could well be extended to include a chapter on the observation that cartilage is a highly hydrated, diseases of connective tissue. In this encyclopaedia fibre-reinforced gel in which resistance to tensile each authority writes on aspects of science, defining stress is largely a property of type II collagen and what is not known, not what is. What do we not resistance to compressive stress a property of the know of the diseases of connective tissue? proteoglycans (Elliott and Gardner, 1978), their J Clin Pathol: first published as 10.1136/jcp.31.Suppl_12.223 on 1 January 1978. Downloaded from

226 D. L. Gardner aggregates, and the associated water. Mature hyaline between the bone rudiments of the embryonic limb cartilage is avascular and aneural. Although chon- alter the properties and appearance of the connective drocytes respire at relatively low 02 tensions the loss tissue matrix so that it becomes fluid. There is no during histological preparation of the normal arti- 'space'. The articulation is a continuum in which cular arterial blood supply, exposure to abnormally movement is permitted in the fluid centre of a bone- low 02 tension, dehydration, and protein denatura- hyaline cartilage-synovial fluid-hyaline cartilage- tion (fixation) must all, by definition, alter and bone structure. distort the very chemical and physical attributes The articular cartilage surface seen in the living that determine the uniqueness of cartilage as a human synovial joint in the surgical operating theatre biological material. is apparently smooth. Light is reflected brightly from Momentary thought will remind the observer the anatomical cartilage contours and there is no that synovial joints do not have 'spaces' or cavities sign of detailed irregularity. This is the appearance in vivo. Articulations form in utero when physical and recognised by William Hunter (1742-43), by Barnett chemical changes in the lying et al. (1961), and by Davies (1969). However, as a

*.@&~~*4

Fig. 1(a), (b) Photomicrographs ofsurface offresh, unstained, and unfixed hyaline human articular

cartilage from lateral condyle of copyright. knee of 13-year-old girl. Pale -ovoid features at top left corners and left centres are fluid droplets ( x 150). t, c .,(a)Cartilage viewed in incident white light under conventional light microscopic conditions. (b) Same field viewed with incident green light, wavelength 550 nm, under interference

~@f~

...... indicate distance ... 100-tm .-::.:'( (reproduced by courtesy of Dr R. B. Longmore). on October 2, 2021 by guest. Protected

b J Clin Pathol: first published as 10.1136/jcp.31.Suppl_12.223 on 1 January 1978. Downloaded from

Diseases of connective tissue: a consensus 227 McCutchen (1978) points out, Davies et al. (1962) High resolution SEM suggests that the articular detected surface waviness no higher than 500 A over surface is formed of interlacing collagen bundles. lengths of 5 ,m and 0-2 ,um over distances of 10 p,m, Preparation for SEM normally necessitates fixing but stated the surfaces were 'smooth'. Yet a 0-2 ,um and dehydrating the material before it is exposed to pit 10 ,um in diameter has sides that slope at more the electron beam under conditions of high vacuum. than 20. Virtually all water is removed; the proteoglycans Not suprisingly, therefore, incident light (Gardner are inevitably displaced on to the resilient super- and McGillivray, 1971a, b) and scanning electron ficial collagen bundles as water is lost. Presumably microscopy (SEM) (McCall, 1968; Gardner and because of this displacement the presence of the Woodward, 1968, 1969; Inoue et al., 1969; Walker very large proteoglycan molecules is not easily et al., 1969) showed that adult and embryo mamma- confirmed by SEM. lian and avian articular cartilage surfaces, apparently When the same surfaces are examined by trans- smooth when seen first at disarticulation, are deli- mission electron microscopy (TEM) in thin, per- cately irregular and detectably rough when examined pendicular sections of well-prepared material, such moist or dry in the unloaded, in-vitro condition as the baboon femoral condyles we have examined (Fig. 1). recently, the articular surface is shown to be formed The surface is shaped grossly by anatomical not of mature collagen bundles with conspicuous contours. A hand lens reveals that the contours cross-striations but of a lamina of uncertain com- bear 04-05 mm irregularities. A stereoscopic position about 60 nm thick. This is the layer depicted, dissecting or incident light microscope then displays described, and analysed by Balazs et al. (1966) and a fine pattern of haphazardly disposed tertiary shown by other authors including Bjelle and hollows and undulations. The pattern is neither Sundstrom (1975). The observations of Balazs et al. orderly nor readily explicable in anatomical terms. were on cattle material, those of Bjelle and Even with acutely angled incident light arranged to Sundstr6m on human. The weight-bearing surface accentuate shadow and contour the detailed is therefore not the misleadingly conspicuous structure of the surface hollows is not easily seen; collagen mat seen by SEM but a very thin, delicate, much of the incident light passes into or through the ultra-microscopic lamina-perhaps hyaluronate copyright. cartilage, outlining the component chondrocytes. (Balazs et al., 1966), perhaps glycoprotein-enmeshed When the arterial supply to the limb is cut off by (Fig. 2) with the most superficial collagen bundles a clamp or tourniquet the appearances ofthe exposed on its deeper aspects and in molecular continuity hyaline cartilage quickly change. Drying accelerates; with the hyaluronate-protein of the synovial fluid the 'highlights' that result from the reflection of in- on its superficial aspect. Preliminary observations cident light from the surface disappear; and small, also reveal the presence of this lamina on the pale, circumscribed zones of pallor suddenly emerge, femoral condylar surfaces of rat hyaline cartilage. each the diameter of a surface undulation or of an Perhaps a finite term, lamina obscurans, should be underlying chondrocyte. used to describe this 60-nm layer to emphasise its Debate still continues vigorously on the nature distinction from the 2-10-,um lamina splendens of http://jcp.bmj.com/ of the surface tertiary irregularities and on whether MacConnail identified by light microscopy. they are caused or influenced by artefact (Clarke, There are indications, therefore, that our know- 1973; Ghadially et al., 1976; Ghadially, 1978). It is ledge of hyaline articular cartilagenous surfaces is certain that the tertiary surface undulations are incomplete. The high water content of hyaline invariably present on fresh unfixed, unloaded, cartilage and the ease with which the surface mammalian hyaline articular cartilage examined structure can be distorted mean that any experiment under conditions that obviate drying (but in the in which drying is permitted or encouraged is bound on October 2, 2021 by guest. Protected absence of a direct articular blood supply). In these to introduce severe artefact. This can be avoided circumstances the 20-40 ,um diameter undulations to a considerable extent by observing and measuring can be measured by reflected light interference freshly excised cartilage by techniques such as microscopy (Longmore and Gardner, 1978) and reflected light interference microscopy that permit their height, diameter, and frequency shown to moist material to be analysed untouched. But the change with age (Longmore and Gardner, 1975). It limit of optical resolution by this method is ± i is equally certain that fine, ridge-like artefacts, wavelength of the monochromatic light chosen for seen by SEM, can be introduced at joint surface analysis. Inevitably the next approach to the surface margins by compression or distortion (Ghadially of load-bearing cartilage must be with low-tempera- et al., 1976). However, the artefactual ridges can be ture analytical methods that allow the techniques avoided by adopting 'optimal' preparative techniques of high resolution SEM and TEM to be applied (Cameron et al., 1976). to fresh cartilage held at low temperature with J Clin Pathol: first published as 10.1136/jcp.31.Suppl_12.223 on 1 January 1978. Downloaded from

228 D. L. Gardner

41 Z

MN

Fig. 2 Surface lamina obscurans oflateral femoral condylar 4T cartilage ofbaboon. At top: stellate arrays ofelectron-dense material, presumably synovial fluid hyaluronate-protein. At centre: lamina obscurans, mainly featureless with no apparent collagenous or proteoglycan structure, merging with (at bottom) surface layer oflarge collagen fibres that extend deeply to comprise the lamina splendens. (Epon-embedded material, uranyl acetate, lead citrate stained x 112000) copyright. http://jcp.bmj.com/

collagen, proteoglycan, and water in their normal It is almost always valuable to examine a model to in-vivo spatial relationships. We may state this elucidate the natural history of a disease. But it is proposition in another way: except for the single, not necessary to choose a model that exactly preliminary photograph published by Cameron et al. replicates each feature of the disease under in- on October 2, 2021 by guest. Protected (1976) no one has yet seen or photographed at high vestigation. A model serves to throw light on aspects resolution intact, normal articular hyaline cartilage of the disease, clarifying pathogenesis rather than surfaces in the fully hydrated state. Judged from exactly reduplicating it. 'Models' of rheumatoid progress in understanding cartilage surfaces in arthritis are therefore often analogues not replicas. perpendicular section, the results may be surprising. With this in mind, the observation that there is no exact replica in any animal species of rheumatoid IS THERE AN ANIMAL MODEL OF arthritis is of great interest but it does not prevent RHEUMATOID ARTHRITIS? valuable experiments with analogues from pro- ceeding. To illustrate the manner in which recent A model, in the sense in which this word has come to be investigations have thrown light on rheumatoid used apropos ofscientific investigation, is a symbol that is polyarthritis without entirely explaining its nature being used as an instrument (Arnold Toynbee, 1972). and origin we may reasonably consider (1) anti- J Clin Pathol: first published as 10.1136/jcp.31.Suppl_12.223 on 1 January 1978. Downloaded from

Diseases ofconnective tissue: a consensus 229 collagen arthritis (Trentham et al., 1977, 1978) and speculation about the nature of the collagen/ (2) immune complex synovitis (Poole and Coombs, adjuvant relationship. The explanation does not 1977; Poole et al., 1978). appear to be attributable to the persistence of small quantities of proteoglycan in the collagen pre- Anticollagen arthritis parations, although the presence of peptidoglycans It has been known since 1954 that local intradermal in bacterial preparations used in complete adjuvants injection into the skin of rats, but not of other suggests this possibility. mammals, of small but finite quantities of finely Evidently, therefore, a new model of experimental ground, heat-killed mycobacteria suspended evenly arthritis of exceptional interest has been devised. in mineral oil (Freund's complete adjuvant (CFA)) Already Trentham and his colleagues (Trentham produces a delayed polyarthritis of characteristic et al., 1978) have extended their analysis of the pattern 9 to 17 days later. The arthritis is not a immunological aspects of their model, showing that replica of rheumatoid arthritis but is a valuable the type II collagen triple helix has unique cellular model with which to study aspects of inflamed and humoral immunogenic characteristics as well as joints. The presence of homologous tissue antigens- being most unusually arthritogenic. Obviously for example, synovia or skeletal muscle-is not this immunogenic capacity may be invoked in- necessary for the response to occur and does not directly to explain the persistence of inflammatory determine organ specificity of response, and in- cartilage injury in a variety of human and animal complete adjuvant (ICFA) is ineffective. disorders. It is not so easy to understand why the Trentham et al. (1977) showed that under com- responsible anticollagen response should injure the parable circumstances human, chick, or rat mature margin of the hyaline articular cartilage of rat knee cartilage type II collagen, given in complete or joints while leaving intact the hyaline cartilage of incomplete adjuvant, provoked autoimmune arth- structures such as the trachea. However, increasing ritis in 41 % of 348 injected rats. Type I and type III evidence of collagen polymorphism could be one did not have this effect in 181 control explanation for the selectivity of anticollagen tissue animals and analogous changes were not produced injury, and no doubt this suggestion will shortly be by the injection of human cartilage proteoglycan. examined. copyright. It was also shown that although a control arthritis could be caused by injecting intradermally 0.1 ml Immune complex synovitis CFA containing 10 mg Mycobacterium tuberculosisl The onset of adjuvant arthritis and of collagen ml the CFA adjuvant used for all collagen immuni- arthritis is marked by an acute, exudative inflam- sations, containing 0-5 mg Mycobacterium buty- matory reaction. In the former polymorphs are ricum/ml, did not cause adjuvant arthritis in 30 numerous, in the latter mononuclear cells exert an control animals. Native type II collagen modified by early predominance. Except in these early lesions limited pepsin digestion still caused arthritis, sug- neither response resembles rheumatoid polyarthritis gesting that type-specific determinants in the helical in man particularly closely. Indeed, in some respects, region of the collagen molecule were responsible for including the rapidly progressive osteoclastic bone http://jcp.bmj.com/ the disease, and oxl (II) chains were not arthritogenic. destruction with exuberant new bone formation, the The experimental type II collagen arthritis is analogy between adjuvant arthritis and human apparently the only model of arthritis in which disease recalls the microscopic changes of granu- disease can be regularly induced with incomplete Jomatous disorders such as leprosy rather than the adjuvant together with homologous tissue injected less destructive, chronic non-specific inflammation intradermally. The suggestion has been made that of rheumatoid arthritis. But the interest of these

this is an unusual property attributable to type II experimental animal disorders to students of on October 2, 2021 by guest. Protected collagen. The resultant arthritis is similar to, but rheumatoid arthritis lies not in the reduplication of not identical with, the polyarthritis following ad- the characteristic histological features of this disease juvant alone. Among the differences are that anti- but in the way in which they show how, in principle, collagen arthritis is more often monarticular, does tissue-damaging mechanisms can follow immuno- not extend, and is not accompanied by mucosal logical injury. lesions. In our experience, adjuvant arthritis can be I therefore argue that the identification in ex- regularly caused in more than 90 % of rats injected perimental animal arthritis models of tissue lesions with CFA. The frequency of the response in anti- with those of human rheumatoid arthritis is neither collagen arthritis is clearly lower. Since the presence to be anticipated nor expected. There is no exact of both the triple helix of type II collagen and an oil, animal model of rheumatoid arthritis. We know of as incomplete adjuvant, are both essential for the no animal in which small finger and toejoints become development of anticollagen arthritis there is inflamed in early- to middle-aged females and in J Clin Pathol: first published as 10.1136/jcp.31.Suppl_12.223 on 1 January 1978. Downloaded from

230 D. L. Gardner which systemic disturbances-including anaemia, cartilagenous (Table 2), and other soft tissue (Table fever, altered plasma protein levels, and a remitting, 3) neoplasms is in its infancy: their study is still in the polyarticular joint disease-progress over half a life first, descriptive stage of scientific inquiry. However, time to fibrous ankylosis, accompanied, quite advances are being made and the widespread use of commonly, by systemic lesions and followed, in one- transmission electron microscopy (Dische et al., fifth of instances, by inexorable amyloidosis. There 1978; Winkelmann et al., 1978) is adding to our is no known animal replica of this state. However, understanding of the cellular nature of these this need not occasion surprise: if the hypothetical disorders and improving classification. The analy- agent causing rheumatoid arthritis could be isolated tical aspects of human connective tissue neoplasia and administered by an appropriate route to, say, have been delayed by the rarity of the lesions in a rhesus monkey or a dog there is every reason to clinical practice and by the difficulty of obtaining expect a response that is species specific and fresh material suitable for modern analytical and characteristically different from that in man. biological techniques of study. Much more is known Consequently those authors who, because they of the experimental neoplasms caused in other have caused microscopic changes in the synovial species. joints of an animal that closely resemble those in Are there then clues to the origin of the connective the human condition, imply that they have directly tissue neoplasms in the evidence presented today on advanced understanding of the pathogenesis of cell structure and behaviour? Can we, for example, human rheumatoid arthritis do not represent the point of their experiments completely. Table 1 Neoplasms of the synovium (after Fechner, Among many recent papers in which this argument 1976) is implicit, if not explicit, are the recent reports of Benign Poole and Coombs (1977) and of Poole et al. (1978). Synovioma The title of both papers includes the phrase Haemangioma 'rheumatoid-like' in relation to the investigation of Lipoma the synovial changes that develop in rabbits when Malignant challenged with foreign protein in such a way that a copyright. Primary response of 'serum-sickness' type ensues. But the Synovial sarcoma importance of these reports does not lie in the Epithelioid sarcoma Clear cell sarcoma closeness with which the joint lesions recall those of Malignant giant cell tumour of tendon the early human disease. The human lesions, after sheaths and soft tissue all, are characteristic but not in themselves patho- Synovial chondrosarcoma gnomonic (Gardner, 1972). The reports are of Metastatic value because for the first time they properly describe Neoplasm-like disorders of synovia this form of immune complex synovitis in micro- Synovial chondromatosis to reminded Pigmented villonodular synovitis scopic detail. It is valuable be (Poole http://jcp.bmj.com/ Intra-articular localised nodular synovitis and Coombs, 1977) that although experimental Extra-articular localised nodular synovitis 'serum sickness' polyarthritis was clearly documented Ganglion and synovial cyst by Klinge (1929) and mentioned by Hawn and Janeway (1947) neither investigator provided detailed microscopic descriptions of the consequent tissue Table 2 Neoplasms of cartilage (Jaffe, 1969) changes. But it is irrelevant to our understanding of Benign human rheumatoid arthritis to extend the pro- Chondroma

Osteochondroma on October 2, 2021 by guest. Protected position by suggesting that the rabbit model rep- Chondromyxoid fibroma licates the human disease histologically: the model Chondroblastoma is a Toynbee analogue, not a replica. Malignant Chondrosarcoma THE NATURE OF CONNECTIVE Chondrosarcoma of soft parts WHAT IS Malignant chondroblastoma TISSUE NEOPLASIA ? Chordoma Cancer is a biological phenomenon whose elucidation is Neoplasm-like disorders of cartilage bound up with advances in a number ofkeyfields ofpresent Chondroid metaplasia Dyschondroplasia day biology. There is no single cause (Julian Huxley, 1958). Chondrodystrophies Ectopic cartilage We know practically nothing of the causes of the Fracture callus human connective tissue neoplasms. They are many Chondroid material of 'mixed' tumours and diverse. The oncology of the synovial (Table 1), and teratomata J Clin Pathol: first published as 10.1136/jcp.31.Suppl_12.223 on 1 January 1978. Downloaded from

Diseases of connective tissue: a consensus 231 Table 3 Neoplasms offibrous tissue (fibromas) relate the analysis of the normal chondrocyte to the (Enzinger et al., 1969) natural history of chondrocytes in chondroid chondroblastoma, chon- Fibromas metaplasia, chondroma, Fibroma durum dromyxoid fibroma, and chondrosarcoma and to Fibroma molle (fibrolipoma) the growth of ectopic cartilage, to the cartilage of Dermatofibroma (histiocytoma , sclerosing haemangioma) fracture callus in delayed healing, and to the carti- Elastofibroma (dorsi) lage component of 'mixed' tumours and of the Neoplasm-like disorders of fibrous tissue (fibromatosis) teratomata? Cicatricial fibromatosis Keloid One result of the new investigations outlined in the Nodular fasciitis (pseudosarcomatous earlier papers of this symposium will be an upsurge fibromatosis) in the biochemistry and cytology of the Irradiation fibromatosis in interest Penile fibromatosis (Peyronie's disease) human connective tissue neoplasms. When a Fibromatosis coli chemical and morphological study has been com- Palmar fibromatosis Juvenile aponeurotic fibroma (calcifying pleted we may hope that, at worst, a new logical fibroma) classification will be available and, at best, new light Plantar fibromatosis Nasopharyngeal fibroma (juvenile will have been thrown on the origin and cellular angiofibroma) relationships of these tumours. In preliminary Abdominal fibromatosis (abdominal inquiries of this nature we have begun to correlate desmoid) Fibromatosis or aggressive fibromatosis the microscopy, electron microscopy, and bio- (extra-abdominal desmoid) chemical composition of selected connective tissue Congenital generalised fibromatosis neoplasms. For example, a myxoma of the mandible Dermatofibrosarcoma protuberans Fibrosarcoma (Fig. 3) in a girl aged 17 years was found to contain copyright.

Fig. 3 Mvifxomia of mndafctible (scale = rentimityetres) ofgirl caged 17 Years. Electi-ottoiniicro - scopt showvsed predominance of poor-ly, difflerentiated mtnxoid http://jcp.bmj.com/ cells. Ont chemical anahlsis tmiatrix- conztacinled ai pr-e- domninance of htvaluronic acid (reproducedbhr courtesy of Dr P. S. Hasletoni). on October 2, 2021 by guest. Protected

I I I I I 0 J Clin Pathol: first published as 10.1136/jcp.31.Suppl_12.223 on 1 January 1978. Downloaded from

232 D. L. Gadrner much hyaluronic acid. The neoplastic tissue was connective tissue neoplasms from generalisations identified as 'myxoic1' by light and by electron arising from the present discussion? The analyses microscopy. In anotheir example, a mesothelioma of made by Abercrombie (1978), Fell (1978), Stockwell pleura of high cellulariity contained connective tissue (1978), and Sloper et al. (1978) have done more than stroma in which col]lagen and sulphated glycosa- concentrate our minds on current knowledge of minoglycans were tthe preponderant molecular some of the most important connective tissue cells. species. These instances show that almost all the They have given us a new perspective of the out- analytical techniques mentioned in this symposium standing problems in the neoplastic and neoplasm- could be brought to bear on the difficult question of like disease of the connective tissues. We can begin the nature of the fibrous, cartilagenous, and synovial to relate views on the behaviour of normal cartilage neoplasms, encouragring new understanding and cells to the natural history of the cartilagenous classification. Already cartilagenous neoplasms have neoplasms and of the teratomata and to extrapolate been identified that display endocrine functions from the normal synovial cell to the monophasic (Mack et al., 1977). (Mackenzie, 1977) and biphasic synovial sarcomata Can we obtain other clues to the behaviour of the (Fig. 4).

Fig. 4 Synovial sarcoma, biphasic. Epithelial cells at upper right; stromal cells at lower left. .-The two components are copyright. .' ' ; . 1 .i fseparated. by an incomplete- ;g .b ...... g ' ' ,; : .: appearing basal lamina (reproduced by courtesy of 5 F. E. Dische and the Editor, .is...... DrJoumnal of Pathology) (x 1260).

...... i^e-. .'^.... ihsc pteil¢lsa pe WiH' $-XEaw-S+ http://jcp.bmj.com/ A .4

.l...... e

~~~~~~~~~.3i8, on October 2, 2021 by guest. Protected J Clin Pathol: first published as 10.1136/jcp.31.Suppl_12.223 on 1 January 1978. Downloaded from

Diseases of connective tissue: a consensus 233

A broad hint comes from analyses of the pheno- One explanation for the abnormal expression of typic expression of the synoviocyte and chondrocyte. neoplastic synovial and chondroid cells is a fault in A clone of synovial cells or chondrocytes in culture the feed-back mechanisms by which the quantity might, it could be supposed, behave uniformly or quality, or both, of matrix components regulates under uniform conditions. But cultural conditions connective tissue cell gene expression. It is established cannot remain constant. When to changes in pH, that the extracellular matrix exerts an important role potential, metabolite accumulation, and in regulating the synthetic and secretory activities ageing are added physical, mechanical, or chemical of connective tissue cells (Grobstein, 1975). Much is disturbances we are not surprised that the mor- now known of the synthesis of the extracellular phology and of the cultured cells change. matrix components, and there is growing under- The direction of change is determined by the nature standing of the ways in which synthesis and secretion of the stimulus. If under the influence of inherited, are regulated. It is also becoming clear that the chemical, viral, immunological, or physical stimuli macromolecules of the matrix themselves control synovioblasts begin to multiply in the uncontrolled cell activities such as glycosaminoglycan synthesis and purposeless manner characteristic of neoplasia (Meier and Hay, 1975) and fibroblast migration is it surprising that in different individuals of distinct (Toole, 1976). Comparable regulatory mechanisms race, age, and sex and in a variety of anatomical affect chondrocyte behaviour, and collagenase or situations the cancer cell should result in gross hyaluronidase, for example, increase macromole- morphological disorders of widely differing appear- cular synthesis when added to chick rudiments in ance and behaviour? culture (Fitton-Jackson, 1970). Much the -same argument may help us to under- It may be resonable to conclude that under- stand the extraordinary diversity of disease forms standing of the origins and natural history of the that are identified chemically in or in relation to connective tissue neoplasms will grow rapidly in the cartilage. As Sokoloff (1976) and his colleagues have coming decade as knowledge of normal connective shown in their experiments on chondrocyte culture tissue cell behaviour increases. Nevertheless, com-

the alteration from monolayer to spinner culture pared with the efforts being expended to understand copyright. conditions determines large quantitative and impor- rheumatoid arthritis and osteoarthrosis, present tant qualitative changes in the molecular species investigations of the pathological physiology of the manufactured and exported by these cells. The neoplastic disorders seem relatively slight. genetic structure of the cell remains unaltered but a variety of metabolic, growth, and synthetic pro- Classification of connective tissue diseases cesses are derepressed, while others are switched-off. The consequences appear to the biologist to be as The classification (Tables 4-11) and nomenclature of diverse as do the neoplastic or neoplastic-like connective tissue diseases are among the controver- cartilagenous diseases to the pathologist. sial questions that remain of outstanding importance

If it is supposed that all chondrocytes are endowed to diagnostic pathologists. As cell and biochemical http://jcp.bmj.com/ with identical genetic programmes then each should genetics have advanced so more and more of the behave in an identical fashion under identical en- disorders attributable to mutant genes of large or vironmental circumstances. This can reasonably be small effect have been defined in terms of faults in assumed for a monoclonal cell culture. If the cells limited parts of single structural or enzymic proteins that come to form, say, a benign ecchondroma of the or in other molecular species. For many years the second metacarpal head in a young man multiply without purpose or control then it is entirely logical Table 4 Inherited diseases of connective tissue on October 2, 2021 by guest. Protected to deduce that changes in the local environment have promoted this disorderly, neoplastic growth. In a Disease Examples substantial number of instances of cartilagenous Chromosomal abnormalities neoplasms there is clinical evidence of an underlying genetic defect. Although the chondrodystrophies, Mutant genes Dominant Achondroplasia, chondrodystrophia fetalis, and multiple ecchondro- polydactyly matosis all exhibit the criteria of inherited ab- Recessive Many of the 'metabolic' disorders. normality, and although chondroma and congenital hypophosphatasia chondrosarcoma may originate on the basis of Multifactorial inherited disorders of cartilage, it seems certain that Some forms of secondary osteoarthrosis, Perthes's diseas the true cartilagenous (and synovial) neoplasms HLA-related are finally promoted by environmental stimuli the Ankylosing spondylitis, the 'reactive' arthritides nature of which we are almost entirely unaware. J Clin Pathol: first published as 10.1136/jcp.31.Suppl_12.223 on 1 January 1978. Downloaded from

234 D. L. Gardner

Table 5 Inflammatory diseases of connective tissue Table 9 Chemical diseases of connective tissue Disease Examples Disease Examples Acute Behcet's syndrome Regional, geographical Kashin-Beck disease, Lysosomal endemic familial arthritis of 'Storage' diseases Malnad Chronic Inflammatory Sarcoid, Crohn's disease Occupational Fluorosis Fibrotic Keloid, systemic sclerosis, Dupuytren's contracture, Therapeutic, (may be familial, dominant iatrogenic Osmic acid, characteristics), Peyronie's radioactive gold, disease radioactive yttrium, bismuth arthropathy Table 10 Metabolic and nutritional diseases of connective tissue (many of the metabolic disorders are Table 6 Immunological diseases of connective tissue heritable) Disease Examples Disease Examples Hypersensitivity Disorders of nucleic acid metabolism Serum sickness, polyarteritis, Gout nodular vasculitis, temporal Disorders of collagen arteritis, giant cell arteritis Faults in hydroxylation Scurvy Immune deficiency Faults in glycosylation ? Diabetic Agammaglobulinaemia, glomerulosclerosis Job's syndrome Faults in procollagen Floppy mitral valve syndrome Autoimmune peptidase (Ehlers-Danlos type) Systemic lupus erythematosus, Faults in cross-linking Osteolathyrism, rheumatoid arthritis, Menkes's kinky hair syndrome juvenile polyarthritis, Faults of uncertain aetiology Marfan's syndrome, rheumatic fever osteogenesis imperfecta,

homocysteinuria, copyright. alkaptonuria Disorders of proteoglycan The GAG storage diseases Disorders of elastic material Disorders of basal laminae Diabetes mellitus Table 7 Infective diseases of connective tissue Disorders of other proteins Amyloid Disorders of amino-acids Alkaptonuria Disease Examples Disorders of mineralisation Chondrocalcinosis, apatite-deposition disease Viral Rubella, mumps, arthritis Table 11 Connective tissue diseases of ageing; and variola J neoplastic, endocrine, and miscellaneous connective Bacterial tissue diseases

Chlamydial, http://jcp.bmj.com/ gonococcal, . staphylococcal, (arthritis Diseases Examples tuberculous 'reactive' arthritides Ageing Osteoarthrosis, intervertebral Protozoal disc disease Amoebiasis Neoplastic Metazoal (see Tables 1, 2, 3) Onchocerciasis Primary Fungal Benign Haemangioma, Candida, lipoma, nocardia }arthritisathis giant cell tumour on October 2, 2021 by guest. Protected Malignant Synovioma, clear cell sarcoma Metastatic Neoplastic-like Villonodular synovitis Table 8 Physical diseases of connective tissue Endocrine Pituitary Acromegaly Disease Examples Adrenal Hyperadrenal corticism Thyroid Hypothyroidism Traumatic Direct injury, Parathyroid Hyperparathyroidism fracture-associated haemorrhage (haemophiliac) Miscellaneous Seronegative arthritides, Irradiation x -Irradiation, relapsing polychondritis, V -Irradiation, isotopic thalassaemic osteoarthropathy, hypertrophic pulmonary Embolic Caisson disease osteoarthropathy J Clin Pathol: first published as 10.1136/jcp.31.Suppl_12.223 on 1 January 1978. Downloaded from

Diseases of connective tissue: a consensus 235 term 'rheumatism' served a clinical purpose: it is no than a synoptic term analogous to 'heart failure' or longer adequate. The phrase 'collagen disease' con- 'uraemia'-common descriptive names for super- veyed Klemperer's (1942) views on the nature of ficially similar syndromes caused by a wide range of systemic lupus erythematosus and systemic sclerosis agents that have in common only an identical end (Klemperer et al., 1942): it has now been abandoned stage. because of our failure to shown any primary dis- turbance of collagen in these and related diseases. Conclusion However, understanding of the synthesis, export, and maturation of collagen, elastin, and the proteo- Bindegewebe (connective tissues) were seen by glycans has led to the emergence of categories of Bichat and described by Johannes Muller. Fifty disease that are properly termed diseases of collagen, years after Bichat they formed the key with which elastin, the proteoglycans, and basal laminae. Virchow unlocked the door of cellular pathology. Stimulated by classifications such as those of In turn, they provided Klemperer with a logical McKusick (1972)*, it has become urgently necessary explanation for common features shared by systemic to rename many of the diseases of connective tissue lupus erythematosus, systemic sclerosis, rheumatoid to take account of our understanding of the primary arthritis, dermatomyositis, and polyarteritis nodosa. defect. Just as McKusick paved the way with his The evidence available today allows us to predict concept of mucopolysaccharidoses so Lapiere and even greater advances in knowledge of the con- Nusgens (1976) and Levene (1978a) have elegantly nective tissue diseases during the years to come. demonstrated that the new knowledge of collagen synthesis and maturation can be used to reclassify Many of the views expressed in this paper result from many other connective tissue diseases. Scurvy discussions with my colleagues Drs C. G. Armstrong, becomes a form of acquired proline hydroxylase R. J. Elliott, 0. Hassan, C. J. Kirkpatrick, R. B. deficiency, type VI Ehlers-Danlos syndrome becomes Longmore, Patricia O'Connor, and H. Friedmann. one form of lysyl hydroxylase deficiency, Menkes's I am grateful for their comments and advice. disease becomes one of the defects of collagen cross-linking, and so on. Comparable logic is now The investigations described in this paper would copyright. applicable in the case of McKusick's own classi- not have been possible without the continued fications. The cumbersome old term 'mucopoly- support of the Arthritis and Rheumatism Council saccharidosis' can be set on one side, and the in- for Research. herited defects of the lysosomal hydrolases that culminate in inadequate degradation of the gly- cosaminoglycans can be grouped as the inherited References glycosaminoglycan storage diseases. These can in- Abercrombie, M. (1978). Fibroblasts. Journal of Clinical dividually be termed, for example, c1-L-iduronidase Pathology, 31, Supplement (Royal College of Patho- deficiency (IH), heparan N-sulphatase deficiency, logists), 12, 1-6. N-acetylgalactosamine H-sulphatase deficiency Ali, S. Y. (1978). New knowledge of osteoarthrosis. http://jcp.bmj.com/ (severe), and so on. Journal of Clinical Pathology, 31, Supplement (Royal We are nearing the time when osteoarthrosis, gout, College of Pathologists), 12, 191-199. rheumatoid arthritis, and intervertebral disc disease Bailey, A. J. (1978). Collagen and elastin fibres. Journal can be approached in a similar manner. Primary of Clinical Pathology, 31, Supplement (Royal College of generalised osteoarthrosis has long been separated Pathologists), 12, 49-58. from the so-called common secondary forms. We Balazs, E. A., Bloom, G. D., and Swann, D. A. (1966). Fine structure and glycosaminoglycan content of the can now recognise clearly the pathological character- surface layer of articular cartilage. Federation Pro- on October 2, 2021 by guest. Protected istics of such forms as idiopathic avascular femoral ceedings, 25, 1813-1816. head necrosis, analgesic osteoarthrosis, bismuth Ball, J. (1978). New knowledge of intervertebral disc arthropathy, and neurogenic arthropathy. It is, I disease. Journal of Clinical Pathology, 31, Supplement believe, only a matter of time before the inclusive (Royal College of Pathologists), 12, 200-204. word osteoarthrosis comes to be regarded as no more Barnett, C. H., Davies, D. V., and MacConaill, M. A. (1961). Synovial Joints: their Structure and Mechanics. *McKusick (1976) claims that while 'the Mendelian Longmans, Green, London. disorders of collagen, elastin and mucopolysaccharide Bitensky, L. (1978). Lysosomes and the connective- are the true disorders of connective tissue', others such tissue diesases. Journal of Clinical Pathology, 31, as rheumatoid arthritis, systemic lupus erythematosus, Supplement (Royal College of Pathologists), 12, and systemic sclerosis 'are disorders in but not of con- 105-116. nective tissue'. I do not believe that is an acceptable Bjelle, A. O., and Sundstrom, B. K. G. (1975). An ultra- analysis. structural study of the articular cartilage in calcium J Clin Pathol: first published as 10.1136/jcp.31.Suppl_12.223 on 1 January 1978. Downloaded from

236 D. L. Gardner pyrophosphate dihydrate (CPPD) crystal deposition Ebringer, R. W., Cawdell, D. R., Cowling, P,, and disease (chondrocalcinosis articularis). Calcified Tissue Ebringer, A. (1978). Sequential studies in ankylosing Research, 19, 63-71. spondylitis. Association of Klebsiella pneumoniae with Bock, P. (1978). Histochemical demonstration of Type active disease. Annals of the Rheumatic Diseases, 37, IV collagen in the renal glomerulus. Histochemistry, 146-151. 0 55, 269-270 Elliott, R. J., and Gardner, D. L. (1978). Changes with age Brewerton, D. A. (1978). HLA system and rheumatic in the glycosaminoglycans ofhuman articular cartilage. disease. Journal of Clinical Pathology, 31, Supplement Annals of the Rheumatic Diseases, 37 (in press). (Royal College of Pathologists), 12, 117-119. Elmes, P. C., and Wagner, J. C. (1978). Fibrosis of the Brewerton, D. A., Caffrey, M., Hart, F. D., James, lung-an environmental disease? Journal of Clinical D. C. O., Nicholls, A., and Sturrock, R. D. (1973). Pathology, 31, Supplement (Royal College of Patho- Ankylosing spondylitis and HL-A 27. Lancet, 1, 904- logists), 12, 158-164. 907. Encyclopedia of Ignorance (1977). Edited by R. Duncan Byers, P. D., Contepomi, C. A., and Farkas, T. A. (1970). and M. Weston-Smith. Pergamon, Oxford. A post-mortem study of the hip joint, including the Enzinger, F. M., Lattes, R., and Torloni, H. (1969). prevalence of the features of the right side. Annals ofthe Histological Typing of Soft Tissue Tumours. World Rheumatic Diseases, 29, 15-31. Health Organisation, Geneva. Cameron, C. H. S., Gardner, D. L., and Longmore, R. B. Fechner, R. E. (1976). Neoplasms and neoplasm-like (1976). The preparation of human articular cartilage lesions of the synovium. In and Joints, edited by forscanningelectron microscopy. JournalofMicroscopy, L. V. Ackerman, H. J. Spjut, and M. R. Abell, pp. 157- 108, 1-12. 186. Williams and Wilkins, Baltimore. Clarke, I. C. (1973). Correlation of SEM: replication and Fell, H. B. (1978). Synoviocytes. Journal ofClinicalPatho- light microscopy studies of the bearing-surfaces in logy, 31, Supplement (Royal College of Pathologists), human joints. Scanning Electron Microscopy (Part III). 12, 14-24. Proceedings of the Workshop on Scanning Electron Fitton-Jackson, S. (1970). Environmental control of Microscopy in Pathology. IIT Research Institute, macromolecular synthesis in cartilage and bone: Chicago. morphogenetic response to hyaluronidase. Proceedings Davies, D. V. (1969). The Biology of Joints. In Textbook of the Royal Society ofLondon, B, Biological Sciences, ofthe Rheumatic Diseases, edited by W. S. C. Copeman, 175, 405-453. 4th edition, pp. 40-86. E. & S. Livingstone, Edinburgh Gardner, D. L. (1972). The Pathology of Rheumatoid copyright. and London. Arthritis. Edward Arnold, London. Davies, D. V., Barnett, C. H., Cochrane, W., and Gardner, D. L. (1965). Pathology ofthe Connective Tissue Palfrey, A. J. (1962). Electron microscopy of articular Diseases (2nd edition in preparation). Edward cartilage in the young adult rabbit. Annals of the Arnold, London. Rheumatic Diseases, 21, 11-22. Gardner, D. L., Elliot, R. J., Armstrong, C. G., and Dean, M. F. (1978). Replacement therapy in the muco- Longmore, R. B. (1978). The relationship between age, polysaccharidoses. Journal of Clinical Pathology, 31, the thickness, surface structure, compliance and Supplement (Royal College of Pathologists), 12, composition of human femoral head articular cartilage. 120-127. In The Aetiopathogenesis of Osteoarthrosis, edited by Denman, A. M. (1978). Rheumatoid arthritis-a virus G. Nuki. Pitman Medical, London (in press). disease? Journal of Clinical Pathology, 31, Supplement Gardner, D. L., and McGillivray, D. C. (1971a). Living http://jcp.bmj.com/ (Royal College of Pathologists), 12, 132-143. articular cartilage is not smooth: the structure of Dieppe, P. (1978). New knowledge of chondrocalcinosis. mammalian and avian joint surfaces demonstrated Journal of Clinical Pathology, 31, Supplement (Royal in vivo by immersion incident light microscopy. Annals College of Pathologists), 12, 214-222. of the Rheumatic Diseases, 30, 3-9. Dingle, J. T. (1969). The extracellular secretion of Gardner, D. L., and McGillivray, D. C. (1971b). Surface lysosomal enzymes. In Lysosomes in Pathology and structure of articular cartilage: historical review. Annals Biology, vol. 2, edited by J. T. Dingle and H. B. Fell, of the Rheumatic Diseases, 30, 10-14. pp. 421-436. North Holland, Amsterdam. Gardner, D. L., and Woodward, D. H. (1968). Scanning on October 2, 2021 by guest. Protected Dische, F. E., Darby, A. J., and Howard, E. R. (1978). electron microscopy of articular surfaces. (Letter.) Malignant synovioma: electron microscopical findings Lancet, 2, 1246. in three patients and review of the literature. Journal of Gardner, D. L., and Woodward, D. H. (1969). Scanning Pathology, 124, 149-155. electron microscopy and replica studies of articular Duthie, J. J. R., Stewart, S. M., and McBride, W. H. surfaces of guinea-pig synovial joints. Annals of the (1976). Do diphtheroids cause rheumatoid arthritis? Rheumatic Diseases, 28, 379-391. In Infection and Immunology in the Rheumatic Diseases, Ghadially, F. N. (1978). Fine structure of joints. In The edited by D. C. Dumonde, pp. 171-175. Blackwell, Joints and Synovial Fluid, edited by L. Sokoloff, Vol. 1, Oxford. pp. 105-176. Academic Press, New York and London. Duve, C. de, Pressman, B. C., Gianetto, R., Wattiaux, R., Ghadially, F. N., Ghadially, J. A., Oryschak, A. F., and and Appelmans, F. (1955). Tissue fractionation studies, Yong, N. K. (1976). Experimental production of ridges 6. Intracellular distribution patterns in rat liver tissue. on rabbit articular cartilage: a scanning electron Biochemical Journal, 60, 604-617. microscope study. Journal of Anatomy, 121, 119-132. J Clin Pathol: first published as 10.1136/jcp.31.Suppl_12.223 on 1 January 1978. Downloaded from

Diseases of connective tissue: a consensus 237 Grobstein, C. (1975). Developmental role of inter- Clinical Pathology, 31, Supplement (Royal College of cellular matrix: retrospection and prospection. In Pathologists), 12, 165-173. Extracellular Matrix Influences on Gene Expression, Lewis, R. M., and Schwartz, R. S. (1976). Canine systemic edited by H. C. Slavkin and R. C. Grenlich, pp. 9-18. lupus erythematosus: a communicable disease? In Academic Press, New York and London. Infection and Immunology in the Rheumatic Diseases, Hart, H., and Marmion, B. P. (1977). Rubella virus and edited by D. C. Dumonde, pp. 259-263. Blackwell, rheumatoid arthritis. Annals ofthe Rheumatic Diseases, Oxford. 36, 3-12. Longmore, R. B., and Gardner, D. L. (1975). Develop- Hawn, C. van Z., and Janeway, C. A. (1947). Histologi- ment with age of human articular cartilage surface cal and serological sequences in experimental hyper- structure: a survey by interference microscopy of the sensitivity. Journal of Experimental Medicine, 85, lateral femoral condyle. Annals of the Rheumatic 571-590. Diseases, 34, 26-37. Hobbs, J. R. (1978). Genetic disease and amyloid. Journal Longmore, R. B., and Gardner, D. L. (1978). The surface ofClinical Pathology, 31, Supplement (Royal College of structure of ageing human articular cartilage: a study Pathologists), 12, 128-131. by reflected light interference microscopy (RLIM). Holborow, E. J. (1978). Systemic lupus erythematosus- Journal of Anatomy, 126, 353-365. an autoimmune disease? Journal of Clinical Pathology, McCall, J. G. (1968). Scanning electron microscopy of 31, Supplement (Royal College of Pathologists), 12, articular surfaces. (Letter.) Lancet, 2, 1194. 144-149. McCutchen, C. W. (1978). Lubrication of joints. In Hunter, W. (1742-43). Of the Structure and Diseases The Joints and Synovial Fluid, edited by L. Sokoloff, of Articulating Cartilages. Philosophical Transactions Vol. 1, pp. 437-483. Academic Press, New York and of the Royal Society ofLondon, 42, 514-521. London. Huxley, J. (1958). Biological Aspects of Cancer. George McGee, J. O'D., and Fallon, A. (1978). Hepatic cirrhosis Allen and Unwin, London. -a collagen formative disease? Journal of Clinical Inoue, H., Kodama, T., and Fujita, T. (1969). Scanning Pathology, 31, Supplement (Royal College of Patho- electron microscopy of normal and rheumatoid logists), 12, 150-157. articular cartilages. Archivum Histologicum Japonicum, Mack, G. R., Robey, D. B., and Kurman, R. J. (1977). 30, 425-435. Chondrosarcoma secreting chorionic gonadotropin. Ireland, J. T. (1978). Basement membrane. Journal of Journal of Bone and Joint Surgery, 59-A, 1107-1111.

Clinical Pathology, 31, Supplement (Royal College of Mackenzie, D. H. (1977). Monophasic synovial sarcoma copyright. Pathologists), 12, 59-66. -a histological entity? Histopathology, 1, 151-157. Jackson, D. S. (1978). Collagens. Journal of Clinical McKusick, V. A. (1972). Heritable Disorders of Con- Pathology, 31, Supplement (Royal College of Patho- nective Tissue, 4th edition. C. V. Mosby, St. Louis. logists), 12, 44-48. McKusick, V. A. (1976). Heritable disorders ofconnective Jaffe, H. L. (1969). Tumours and Tumourous Conditions tissue: new clinical and biochemical aspects. In ofthe Bones and Joints. Lea and Febiger, Philadelphia. Advanced Medicine, 12 (Twelfth Symposium on Kimpton, London. Advanced Medicine of the Royal College of Physicians), Jayson, M. I. V. (Ed.) (1977). Symposium on the fibrotic edited by D. K. Peters, pp. 170-191. Pitman Medical, process. Annals of the Rheumatic Diseases, 36, Supple- London. ment 2. Marmion, B. P. (1976). A microbiologist's view of Kefalides, N. A. (1974). Biochemical properties of human investigative rheumatology. In Infection and Immuno- http://jcp.bmj.com/ glomerular basement membrane in normal and dia- logy in the Rheumatic Diseases, edited by D. C. betic kidneys. Journal of Clinical Investigation, 53, Dumonde, pp. 245-258. Blackwell, Oxford. 403-407. Meier, S. and Hay, E. D. (1975). Control of corneal Klemperer, P., Pollack, A. D., and Baehr, G. (1942). differentiation in vitro by extracellular matrix. In Diffuse collagen disease; acute disseminated lupus Extracellular Matrix Influences on Gene Expression, erythematosus and diffuse scleroderma. Journal of the edited by H. C. Slavkin and R. C. Grenlich, pp. 185- American Medical Association, 119, 331-332. 196. Academic Press, New York and London. Klinge, F. (1929). Die Eiweissiiberempfindlichkeit Muir, H. (1978). Proteoglycans of cartilage. Journal of on October 2, 2021 by guest. Protected (Gewebsanaphylaxie) der Gelenke. Experimentelle Clinical Pathology, 31, Supplement (Royal College of pathologisch-anatomische Studie zur Pathogenese des Pathologists), 12, 67-81. Gelenk-Rheumatismus. Beitrdge zur Pathologischen Panayi, G. S. (1976). Antibody-mediated leucocyte Anatomie und zur allgemeinen Pathologie, 83, 185-220. cytotoxicity to human liver cells in rheumatoid arth- Lapiere, C. M., and Nusgens, B. (1976). Collagen patho- ritis and other diseases. Annals of the Rheumatic logy at the molecular level. In Biochemistry ofCollagen, Diseases, 35, 27-31. edited by G. N. Ramachandran and A. H. Reddi, Poole, A. R., and Coombs, R. R. A. (1977). Rheumatoid- pp. 377-447. Plenum Press, New York and London. like joint lesions in rabbits injected intravenously with Levene, C. I. (1978a). Diseases of the collagen molecule. bovine serum. International Archives of Allergy and Journal of Clinical Pathology, 31, Supplement (Royal Applied Immunology, 54, 97-113. College of Pathologists), 12, 82-94. Poole, A. R., Oldham, G., and Coombs, R. R. A. (1978). Levene, C. I. (1978b). Kettle Memorial Lecture. Athero- Early rheumatoid-like lesions in rabbits injected with sclerosis-disease of old age or infancy? Journal of foreign serum; relationship to localization of immune J Clin Pathol: first published as 10.1136/jcp.31.Suppl_12.223 on 1 January 1978. Downloaded from

238 D. L. Gardner complexes in the lining tissues of joints and cellular Barondes, pp. 275-329. Plenum Publishing, New content of synovial fluid. International Archives of York. Allergy and Applied Immunology, 57, 135-145. Toynbee, A. (1972). A Study of History, Oxford Univer- Pope, F. M., and Nicholls, A. C. (1978). Molecular sity Press. London. abnormalities ofcollagen. Journal ofClinical Pathology, Trentham, D. E., Townes, A. S., and Kang, A. H. (1977). 31, Supplement (Royal College of Pathologists), 12, Autoimmunity to type II collagen: an experimental 95-104. model of arthritis. Journal of Experimental Medicine, Schofield, J. D., and Weightman, B. (1978). New 146, 857-868. knowledge of connective tissue ageing. Journal of Trentham, D. E., Townes, A. S., Kang, A. H., and David, Clinical Pathology, 31, Supplement (Royal College of J. R. (1978). Humoral and cellular sensitivity to Pathologists), 12, 174-190. collagen in Type II collagen-induced arthritis in rats. Scott, J. T. (1978). New knowledge of the pathogenesis of Journal of Clinical Investigation, 61, 89-96. gout. Journal of Clinical Pathology, 31, Supplement Walker, P. S., Sikorski, J., Dowson, D., Longfield, M. D., (Royal College of Pathologists), 12, 205-213. Wright, V., and Buckley, T. (1969). Behaviour of Sloper, J. C., Barrett, M. C., and Partridge, T. A. (1978). synovial fluid on surfaces of articular cartilage. A The muscle cell. Journal of Clinical Pathology, 31, scanning electron microscope study. Annals of the Supplement (Royal College of Pathologists), 12, Rheumatic Diseases, 28, 1-14. 25-43. Winkelmann, W., Becker, W., and Cserhati, M. (1978). Sokoloff, L. (1976). Articular chondrocytes in culture. Das Chondrosarkom: ein Beitrag zur feingeweblichen Arthritis and Rheumatism, 19, 426-429. Morphologie. Zeitschrift fur Orthopddie und ihre Stockwell, R. A. (1978). Chondrocytes. Journal of Grenzgebiete, 116, 46-56. Clinical Pathology, 31, Supplement (Royal College of Woolley, D. E., Crossley, M. J., and Evanson, J. M. Pathologists), 12, 7-13. (1977). Collagenase at sites of cartilage erosion in the Taylor-Robinson, D., and Taylor, G. (1976). Do myco- rheumatoid joint. Arthritis and Rheumatism, 20, 1231- plasmas cause rheumatic disease? In Infection and 1239. Immunology in the Rheumatic Diseases, edited by Woolley D. E., Glanville, R. W., Roberts, D. R., and D. C. Dumonde, pp. 177-186. Blackwell, Oxford. Evanson, J. M. (1978). Purification, characterisation Toole, B. P. (1976). Morphogenetic role of glycosamino- and inhibition of human skin collagenase. Biochemical glycans (acid mucopolysaccharides) in brain and other Journal, 169, 265-276. tissues. In Neuronal Recognition, edited by S. H. copyright. http://jcp.bmj.com/ on October 2, 2021 by guest. Protected