Differences Between -Epithelial Junctions in and the Anagen Follicle

Michael Nutbrown and Valerie A. Randall Department of Biomedical Sciences, University of Br~dford , Bradford, U.K.

Although the ultrastructure of the dermal-epidermal similar to modified dermal-melanocyte junctions, in junction has been well characterized, little is known which the intercellular cytoplasmic filaments do not about the junctions between the dermal papilla and come together at an attachment plaque, the laminar the surrounding epithelial cells of the hair bulb, or components tend to be thinner, and the anchoring between the connective tissues and the epithelial fibrils beneath the lamina dens a are fewer. A trilam_ cells on the outside of the . Because the inar membrane also was interposed between the con_ dermal papilla plays a major role in controlling the nective and epithelial tissues on the outside of the hair follicle, we also examined the ultrastructure of follicle, but nothing that resembled a hemidesmo_ the potentially important dermal papilla-epithelial some or any other type of anchoring structure Was junction in normal scalp anagen follicles. The der­ seen. The difference in structure of the junctional mal-epidermal junction in skin was a trilaminar base­ complex between skin and hair follicles probably ment membrane characterized by the anchoring reflects the relatively permanent state of the epider_ points of and tonofilaments in ke­ mis, compared to the dynamic processes involved ratinocytes. In the hair follicle, the junction that during the anagen phase of the hair follicle. Key separated the dermal papilla and epithelial cells was a words: dermal papillah,ltrastrllctllre. ] Invest Dennatol 104: trilaminar , but relatively few 90-94, 1995 putative anchoring points were seen. These were

be structure and ul trastructure of the dermoepider­ here, i. e., basement membrane for light microscopy and basaJ mal junction (DE)) are welJ documented [1-4]; its lamina at the electron-microscope level [16). composition and formation [5,6] and the roles of In transverse sections, the DE] is seen as a basement membrane bemidesmosome attachment points and the various that fo llows an irregular, undulating tin e. Briggaman and Wheeler anchoring m echanlsms in skin are clearly understood [1] described at the ultrastructural level the details of the junction, [7,8].T In co ntrast, most descriptions of the ultras tructure of h air hemldesmosomes, and modified attaclunent points associated with follicles have concentrated on the appearance of the connective melanocytes. The ultrastructure of the junctional zone between the tissue and epithelial celJs, their topographlc orgaruzation with dermal papiLla and epithelial components (DPE]) in mouse and rat respect to each other, and the changes in appearance due to hair folJjcles during early and late catagen also has been examined development and differentiation [9 - 1.2]. Thejunctions between the [17-19]. An additional component, the hyalin membrane, was connective and epithelial tissues in the human hair follicle have described on the outside of the hair follicle [17]. T lus is an outer been neglected, except by PuccineUi et (// [13], probably because the layer of the follicle, adjacent to the , wluch is seen as important role of the connective tissues in the regulation of hair two layers of orthogonall y arranged colJ agen fibers, with the inner growth was not appreciated fully at the time. layer parallel to the long axis of the hair. Puccinelli f t. 01 [13] did not The temlS basement membrane and basa llamlna are both used to describe tlus hyalin membrane in human follicles. describe the thin layer intervenlng between epithelial and connec­ Because the dermal papilla is now known to playa major role in tive tissues. Confusion exists because many biologists have used influencing the form and dynamics of the hair follicle [20,21], "basal lamina" to describe the structure that is now calJed tbe which probably involves regulatory substances crossing the base­ [14]. The terms recommended by the International ment membrane [22], we investigated the ultrastructure of connec­ Anatomical Nomenclature Committee [15] have been adopted tive tissue-epitheljal junctions (CTE]) on the o utside of the hair bulb and around the dermal papi.lla of normal anagen hair follicles. Manuscript rcccivcd Deccmber 22, 1993; rcvised July 8. 1994; acccpted Samples of post-auricular skin were processed as controls. for publication August 12, 1994. MATERJALS AND METHODS A preliminary report of this study was prcsented at thc Ne w Yock Acadcmy of Scicnces, J anuary 1991, Arli.ngton, VA . Collcction of Skin Samplcs Samplcs of normal hU\113.n post-auricular RepriJu requcsts to Dr. M. Nutbrown, Department of Biomedical SkUl were obtained from routine surgical excisions of bcnign lesions and Scicnccs, University of Bradford, Bradford DD7 1 DP, UK. plastic surgery. Samples were imrncrscd irnntcdiately in a solution of 3')10 Abbreviations: CTEJ, CO lmective tissuc-cpithelialjunction; DPEJ, demlai glutaraldehydc in 0.1 M Sorcnsen phosphate buffer at pH 7.2, cut into papilla-cpithelial junction. approximately 2-mm cubes. and transported to the laboratory in the

0022-202X/95/S09.50 • SSDIO022-202X(94)00239-4 • Copyright 1995 by The Society for Invcstigative Dcrmatology, Inc.

90 VOL. 104, NO. 1 J ANUARY 1995 ULTRASTRUCTURE OF HAIR FOLLICLE JUNCTIONS 91

Figure 1. Detail of DE] in post-au­ rieular human skin. Tlus view shows the undulating basal lamina (BL) contain­ ing ~ series of well-defined hemidesmo­ somes joining tile epidemlis (above) to the (below). Attaclul.lent plaques (AP) and tonofilaments (T) form the epitllelial side of the , witll a sub­ basal dcnse plaque (SBDP) contained witlun tile lanuna lucida (LL). Anchoring fibrils (AF) and fibers (C) can be seen subjacent to the lamina densa (LD) in the extracellular matri. .-x of the demus. Bar, 1 I.un.

glutaraldehyde in a sterile container. Scalp biopsy specimens were taken coursing back from the hemidesnlOsome attaclul1ent plaques into fro m the occipitoparietal region of normal scalps from six volunteers with the cytoplasm of the basal cell s. T he and lamina densa informed consent and Ethical Committee approval at the Deonatology were clearly seen as pale and darkly stained bands, respectively, that Department, Leeds General Inflrmary. Punch biopsy specimens of 4 mm in diameter were taken under 1% Lignocaine local an esthesia and inll1lersed faithfully followed the line of the basa.! cell m embranes. The inlmediately in 3% glutaraldehyde in 0.1 M Sorensen phosphate buffer to extracellular space of the dermis was mostly filled with transverse­ check autolytic changes during transport to the laboratory. cut collagen bundles interleaved with the processes of connective tissue cells. Processing of Skin Samples and Individual Hair Follicles Skin tissue was dissected further to yjeld 1-mm cubes, whi ch exposed the Fine structural detail of the junctional zon e and connective tissue subcutaneous DE]. After trinulling, the samples were processed for trans­ is shown in Fig 1. T he lamina lucida was evident though not always mission el ectron mi croscopy within 4 h of excision. Sca lp specimens were very well defined, but in th e lucen t space, sub-basal den se plaques transferred to 35-mm petri dishes in glu taraldehyde solution, where anagen were seen associated with the attachment plaques. Tonofilament hair fo llicles were microdissected from each specimen and transferred ~o a connection to the attachment plaques was very m arked. A sligh t second di sh. T he follicles were cleaned of surrounding tissue and lipid , but increase in staining density of the lamina densa was evident at the the connective tissue sheath was left intact. Primary fi xation of the dissected points w here the membrane passed beneath a sub-basal dense follicles was continued in similar 3% glutaraldehyde for a total time of 3-4 h, including transport time. After the first fixation, subsequent processing plaque and an attachment plaque. Anchoring fibrils were drawn out was done in a Lynx Microscopy T issue Processor (Leica UK Ltd.) . from th eir conn ection with th e lamina densa at one end and All tissues were fixed routinely in glutaraldehyde and osmium tetroxide inserted into the of the dermis at the other; and embedded in Araldite CY 212 epo,,), resin for electron microscopy. som e appeared to be in the form of a loop (Fig 1). In the dermis, collagen bundles and cytoplasmic processes were interspersed with Selection and Examination of Ultrathin Sections T hree control samples of post-auricular skin. from di fFerent donors were sectioned on a strips of longitudinally cut collagen, which displayed characteristic Reichert Ultra cut D ultramicroton1e. Silver to pale gold ultra-thin sections, p eriodic banding. Ancho ring fi lam ents, although not readily obvi­ i.e., about 80 nm in thickness, were cxamincd in two blocks from one ou.s in Fig 1, could be discerned at high er magnification , but so urce of skin and in one from each of the others. Sections were stained with neither dennal microfibril bundles n or anch oring plaques associated uranyl acetate and lead citrate (23) and then examined in either aJEOL 100S with anchorin g fi brils were seen in any of the sections examined . or 100CX transmiss ion electron microscope. Becau se the DEJ is a contin­ uous and ultrastructurally stable environment, onl y two or three sites were The CTE] in the Normal Hair Follicle At the light-micro­ selected in each of the sections examined; these were consid ered represen­ scope level, the basement m embran e of the h air follicle appeared as tative of the junction as a whole. an am orpho us, pale-staining o r fi ne fibrilla.r b and (Fig 2). It formed Hair fo llicles were much more diffi cult to section than skin samples a continuous layer enclosing the dennal p apilla, where it formed an because of the important of orienting the fo llicle correctly to section in the unbroken barrier, and continued around the outer parts of the direction of hair growth and through the center of the follicle. Excess resin was tri.mmed carefully from the block to leave the fo llicle exposed on the follicle betw een the connective tissue sheath and the o uter root top of a broad-based pyramid of resin. Semi-thin survey sections (thickness sheath . U ltrastructural examination revealed a high level of orga­ 350 rlIll) taken at frequent intervals were stained with toluidine blue [24] nization similar to that of the DE). and examined by light mi croscopy. W e adjusted the orientation of the follicle repeatedly until it was aligned, ideally with its long axis pa ra.llel to Outside of the Hair Follicle Electron microscopy of the CTE) the Z axis of the mi crotome and perpendicular to the X and Y planes. T hi s confirmed th e smoothness of the m embrane between the o uter root ideal was not always achieved becau sc follicles arc rarely regular in sha pe; sheath and the connective tissue sh eath. At medium magnification, if any follicl e was twisted or kinked in any way, we exposed as much of the the CTE) appeared as a three-layered structure (positioll 1; Fig 3a), bulb and lower part of the follicle as poss ible for sectioning. Longitudinal which was less undulatory th an the similar structure seen in skin. ultra-tlljn sections of the lower follicle, up to about three times papilla The plasma m embran e of cell s of the outer was very height, were stained and examined as described above. O nly sections cut well defin ed and was invaginated in several places by infoldings through tllC median planes of the follicle were examined. into the cell cytoplasm. T he lamina lucid a was a narrow but easily Eleven fo llicles from the six bi opsy specimens were selected for study; seen clear space b etween the plasma m embrane and th e lamina useful ultra-tlun sections were cut successfully from eight. T he CTEJ was densa, with some particulate content comparable in appearance and exanlincd in detail at six or seven sites in each fo llicle, including the apex, approximate mid-point, and base of the dermal papilla, and three corre­ quantity to that seen in skin. The lamina densa was a sm ooth band sponding sites on tllC outs ide of the follicle; ifpossibl e, an additional site was of uniform thickn ess which at high magnifications had a fme examined at about two times papi.lla height. T hese sites are ma.rked on Fig granw a.r appearance. Subjacent to the lamina densa were the 2 . orthogonal layers of collagen fibers, which make up the hyalin m em bran e. RESULTS T here was no eviden ce of an ything resembling a hemidesmo­ The Skill DE] T he human skin DE) resembled that described in some and no to nofilam ents reaching back into the cytoplasm of other studies [1-3]. Hemidesmosomes were seen lining the plasma cell s of the . Located at irregular intervals along m embran es of the basal (Fig 1), with tonofilaments the m embranes were small clouds of particulate m atter (Fig 3a). 92 NUTI3R.OWN AND RANDALL T H E JOURNAL OF INVESTIGATI VE DERMATOLOGY

N ear the base of the umer part of the lobe (position 4; Fig 3d), the orthogonal arrangement of the collagen layers was broken almost completely, though the fi bers tended to lie parallel to the lamina densa . The orthogonal arrangement of fibers seen on the outsid e of the follicle was never observed within the dermal papilla. T he p la sma membranes of the basal epitheJj al cell s had a few thickenings possibly associated with attachment pOUltS to the basal lamina. T he lamula densa appeared to follow the line of the epithelial plasma membra ne, though there were several widenings of the lamin a lucida. T he lamina lucid a was mostly fIlled with a substance similar Ul stairul1g density and appearance to the cyto­ plasm of the epithelial cells. N o invagulations simil ar to those seen on the outside of the fo llicle were seen in this area. T he interf.lce between the and connective tissue, at mid-papi.lla height (posit ioll 5), was well defined by a sli ghtly undulating line, w lu ch had few gaps or invaginations (Fig 3e). T here were some sJj ght t1u ckenul gs on the plasma membrane, but these were not convincing as attachment plaques. T he lamula lucida clea rl y had an evenly distributed, fine granular content (Fig 3e) . T he lamul a densa was seen as a very thin, well-defined line, which parall eled the course of the epitheJjal cell plasma mem­ Figurc 2. Scction through bulb and lowcr part of human scalp branes. Coll agen fibers were distributed intermittently along the anagcn hair folliclc. The dermal papilla (DP) and epithelial tissues (Epi) length of the junction. T he fi bers amassed nearest to the lamina arc separated by a basement membrane (BM), w hi ch also encloses the entire densa seemed to be preferentiaJJy end-cut. fo llicle. The numbers refer to positions examined in detail in the extern al At the top of the papilla (position 6; Fig 3j), the plasma connective tissue and DPE], described in the text and referred to in Fig membranes displayed several gaps and il1 fo ldil1 gs similar to those on 3a-f Bar, 50 J-Lm. the o utsid e of the hair fo llicle. T hkkenings of the plasma mem­ brane and associated u1Creases in density of the Jamula densa were seen at several points along the junction (F ig 3.1). T he lamina lucida contai.ned an evenly distributed, fine- grained i.ncIusion, and the T hese clouds diffused into the cytoplasm of the epithelial cell s for lamina densa was continuous though of variable density. Coll agen about 2 J-Lm and appeared to stretch across the basa l lamina and into fibers were coll ected Ul i.rreguJarJy sized clumps along the edges of the layer oflongitudinally cut colJ agen that surrounded the fo llicle. the Januna densa. Anchoring fibril- li ke structures were attached at At this upper region of the bulb, the orthogonal arrangement of the one end to the lamina densa of the junction and at the other end colJ agen fiber layers was particularly obvious, with the inner la yer inserted into the extraceUula r matrix of dermal papilla (Fig 1). of longitudinal fib ers lying parallel to the hair folJjcle. Concentrations of fin e fi brillar material, similar to dermal microfi­ Sinlilar features were seen in the CTEJ in the mid-bulb (pos itiol/. bril bundles [1 also were seen in the dermal papilla extracellular 2; Fig 36). Invaginations were more abundant and were more J, matri x. complex than a simple infoldi.ng of the plasma membrane; they Table I summarizes the observations described in the R esllits. produced very long processes that terminated far ba ck into the cytoplasm of celJ s of the outer .root sheath. T here were some D IS C USSION thickenings of particula te matter in the lamina densa accompanjed T he ultrastru cture of the CTEJ has been examilled here Ul two by increascs in density in the lamina lucida, but not always main areas of the human scalp anagen fo lJj cle: on the outside complemented by similar defu sions in the epithelj al cytoplasm, as between the conllective tissue sheath and outer fo llicular tissues described earlier (Fig 3a). T he junctional zone was well defined, from the base of the follicle up to about twice the demlal papilla but not as well as at the level of the papill a (position 6). The collagen height, and on the inside between the dermal papilla and the layers were less well defuled; the fibers were undulatory with a epithelial tissues of the hair bulb. T hese junctions are the CTE] and variable appearance and the circular fibers were irregularly distrib­ the DPE], respectively. Beca use our parallel control samples of skin uted. clearl y showed the normal structures reported fo r the human DE] At the outer lower part of the lobe (posit ion 3; Fig 3c), the [1], our processing technique seem s valid. T he folllcular junctions two-layer coll agen system ceased to exist as such, although the were sinlilar to those seen in the skin; on the outside the junction circular fibers stiJJ were seen to run at right an gles to the axjs of the appeared as a smooth line between the epithelial and connective follicle. Invaginations and infoldings of the plasma mcmbrane still tissue components, whereas where the junction divides the dermal were observed and the lucent space in the basement membra ne was papilla from the epithelial tissue, it was undulatory, though less so obvious, but the lamina densa was very thin and difficult to discern. than U1 the skin. The DPE] T he DPE] (Fig 3d-:/) had a genera ll y less smooth T he basement membrane was resolved ulto the three layers of contour than the similar junction between the outer root sheath and peripheral cell membranes: lamina lucid a, lamula densa, and the the connective ti ssue sheath, but it did not undulate as much as in additional la yers of the hyalin membrane reported in m ouse follicles the skin DE] (compare with Figs 1, 2, 3a). T he matrix cell s that [17J. T he mechankal connection between the hair follicle and the surrounded the dermal papilla were mainly keratinocytes and connective tissue components was much weaker than that between melanocytes. T he means of attaching these cell s to the basal lamina the co.rresponding components ill skin. Nothing was seen that was similar to tbat seen in the dermal-melanocyte junction in skin. corresponded to the skin hemidesmosome with tonofilaments on T he structures (Fig 3e) included tbe dense pJate, sim il ar in appear­ either the external COl1llective tiss ue or dermal papilla junctions. ance to the hemidesmosome attachment plaque, a clear lamina However, the appearance of particulate clouds of matter (Fig 3c) in lucida, and a lamina densa that was not well defined but showed the regions of the lamina densa and adjacent epithelium on the some thkkenmgs in density below the dense plates. T here was no o utside of the folJjcle were reminiscent of the thickening densities evidence of anchOl;ng filaments passing through the lamina lu cida. reported around and below attachment plaques in the dermal­ A true hemidesmosom e structure was not seen in any of 34 melanocyte junction [lJ. T he increases in tissue density may be a ultra-thjn sections of normal hair follicles containing a good view of similar kind of loose anchoring s,tfucture. Putative anchoring the dermal papilla (compare with Figs 1, 3a). structures similar to those described i.n the skin dermal-melan ocyte VOL. 104. N O. I JANUARY 1995 ULTRASTR UCTUR.E OF H AIR FOLLICLE JUNCTIONS 93

Figure 3. Details of the CTEJ 011 the outside of the follicle (a- c) and t he DPEJ (d-j). See text and Fig 2 fo r definitions of positions 1- 6. a: T he junction (positioll 1) between the outer root sheath (fop) and the connective tissue sheath (be/Dill) shows a three-layered strucnlre comprising the basal-cell plas ma membrane (PM), lamina lucida, and lamina densa (LD). Below the j unction are two orthogonal layers oflongi tudinal (CI) and transverse (Ct) collagen fib ers. In vaginations (In) are seen in thi s part of the juncti on. Small clouds of particula te matter arc diffu sed in the epi thelial cell cytoplas m and across the basal lamina in to th e connective tissue layers. Ii: CTEJ at mid-bulb (positioll 2) between the hair matri-" (a liol/e) and the connective tissue sheath (Ii elolll) . There are pronounced invaginations (In) in the bas al -cell plasma membranes. Longitudinal (CI) and transverse (Ct) collagen fi bers persist in orthogonal layers but are not as well defmed as higher in the fo llicle. In fusions of particulate matter (PC) arc present in the lamina densa and connective tiss ue regions, but these do not persist into the epithelial tissues . c: CTEJ in the lower part of the bulb (positio ll 3) between the division zone above and the connective tiss ue sheath. The tril aminar arrangement of the junction (CTE] ) is still evident and th ere arc invaginations (In) in the plasma membra nes, but the ordered composition of the colla gen layers (C) has broken down. d: DPEJ at the base of the papilla (pos itioll 4). T he two-layer orthogonal arrangement of coll agen fibers (C), as seen on the outs ide of th e fo lli cle, is no longer evident. T he juncti on is generally well defined. though the basa l-cell plasma membranes (PM) and lamina densa (LD) arc slightly cli ft" se. e: DPE] at mid-papilla height (positioll 5) has a very well-defined interface with few gaps or invaginations. Slight thickenings (A) of the plas ma membranes on the hair-matrix side are not convin cin g as attachment plaques . Coll agen fi bers (C) in the demlal papill a are much sparser than in lower regions of the follicle. I Pu tative anchoring system in til e DPEl ncar the apex of the papilla (pos it io ll 6). T he presumpti ve is seen above, with the dermal papilla below. T hi s anchoring system, which ha s a few similarities to a helllidesmosome. comprises a dense plate or attachment plaque (D) and a complementa ry thi ckening of the subjacent lamina dellsa only. Anchoring fi brils (AF) protrude into the extracellular matrix (ECM) of the dermal pap illa , and mi crofib ril bundles (MB) arc interconnected with coll agen fi bers. Bars, 0.4 J.l.I11 (a, /I,dj); 0.8 J.l.1ll (c,r).

junctio n also were seen around the top of t he de rmal papilla (Fig 3j). A similar a bsence of substantial an choring compo ne nts can be seen in a single mic rograph of a human de rmal papilla [13], t ho ugh T able I. Characteristics o f the C TEJ in H uma n Anagen Puccinelli et at m ade n o commen t abo ut this in their paper. Hair F ollicles and t h e DEJ H e midesm osom es were rep o rted as absen t also from the rat hair Position in Hair Foll icle matrix basem en t m e mbrane [25]. It is interesting that bullo us p e mphigoid a ntigen , w hich is fo und in associati o n with hemides­ O utside Wall Dermal Papilla mosomes in the D E] [26], w as not present in the D PE] o f human anagen follicles [27] o r in developing hair bulbs in m o use and rat Characteristic 2 3 4 5 6 DEJ skin [28,29]. Epitheli al matrix cell s surro unding the derm al papilla appear to Undulation of basement -/+ - / + + ++ be joi.ned only loosely to the connecti ve-tiss ue compo n en ts, be­ 111 CJ11hran e Hyalin membran e ++ ++ + -/+ cause it is n early impossible to obtain dermal papillae by plucking lnvaginations of pl asma + + + + anage n (30] . T he lack of definite anc ho ring m echanisms in the mC lllbra ne hair-fo llicle junctions m ay all ow fl exibility o f m ovem en t willie th e Hemidesmosome + cells undergo the d yn amic processes of the growth cycle. T he Sub-basa l dense plaque + upward progressio n of the m atri.x e pitheli al cell s [31] and the Dense plate/ attachment -/+ + + proposed d o wnward m ovem en t of cells of the o ute r root sh eath pl aque durin g aJl agen (3 2] would be hig hly restricted if they were tig htly Increased staining of + + + + bound at the epithe lial-connective tiss ue junc ti o ns. lalnina dcnsa + W e observed invagina ti o ns of the plasm a m e mbran es of ceLI s of Anchoring fi brils + Anchoring fi lam ents +/- the oute r ro o t sheath adjacent to the CTE] (Fig 3",c), w hic h Tonofilaments + appare ntly w e re no t described before fo r the human an agen hair 94 NUTBROWN AND RANDALL THE J OURNAL OF INVESTIGATIVE DERMATOLOGY

fo llicle. Parakkal [17] described the convolution of the hyalin 6. Martin GR, Timpl R.: Laminin and oth\!r basement rncmbrane components. A ll" membrane of the rat catagen fo llicle as ca using invaginations of Rw Cell Bioi 3:57-85, 1987 7. B riggam an R.A: Ep id erm al-dermal in teractions in adul t skin. J III vest DCI'II/ aloi adjacent follicular epithelial membranes, but this is not what has 79:21 S-24S, 1982 happened here. Because the invaginations in the hair fo llicle 8. Stanley J R, Woodley DT, Katz SI, Martin Gil..: Structure and function of appeared to be pinocytotic and vesicles were often concentrated in basement membrane. ) Illvesl Derlll alol 79:695-725, 1982 the adjacent areas, this may be a mecharu.sm for the uptake (or 9. Birbcck MSC, Mercer EH : T he electroJl microscopy ofthc human hnir fo Ui de 1. secretion) of material. Sinlilar pinocytoti c vesicles are seen in the In troduction and the hai r cortex. ) Bi0I' II ys Biocllelll C]'tol 3/2:203-214+ PI , 1957 plasma membranes of the basal epithelial cells of skin [1] . N ear the 10. Birbeck MSC, Mercer EH: T he electron microscopy of the human hair fo llicle 2. top of the dermal papilla, there were several gaps in the basal lamina T he hair . ) m opll ]'s Biocllelll C),101312:215-222+ PI , 1957 and infoldings of the plasm a membr311es of the basal cell s. T hese 11. Birbeck M5C, Mercer EH: T he electron microscopy of the hU lllan hair fo llicle 3. gaps or invagillations were simil ar to those described on the o utside T he in ner root sheath and trychohyaline.) Bioph )'s Hiochelll C]'tol 3/2:223_ of the follicle and may serve a sinli1 ar purpose, but li ttle vesicul ar 230 + PI,I957 12. Puccinelli VA, Caputo R, Ceccarelli B: T he structure of the hurnall hair fo llicle presence was noted. and hnir shaft: an clectron microscope study. Giom Il al Derlll 108:453-498, T he differences in attaclun ent points between the connective an d 1967 epitheliaJ tissues are o bvious morphologic characteristics that dis­ 13. Puccin c lH V, Caputo R, Ccccarclii 13: Chnuges in the basement rne mbrnnc of th e tinguish the junction in skin from that of the hair fo llicle. Further pap illa and wall of the human h ~li r fotH clc. Arch Klill E:.."p Dermaw l 233: 172- 183, 1968 studies, such as those by Shimizu et 01 (33] using im munohi sto­ 14·. La uric GW, Leblond CPo Basement membrane nomenclature. N alll rl' 3 13:272, chemistry, could be useful to define the differences between skin 1985 and both types of hair-follicle junctions. It would also be interesting 15. Nomina hjstologica. In : NO li/ ili a A"atomica, part 2. W illiams & W il ki ns, Balti_ to investigate Ch311ges to both ultrastructure and immunomorphol­ more, 1983, p H 6 16. RD." MH, R omrell LJ : Epithelium. In : Histology-A Text all d Atlas. W illi ams & ogy during the hair cycle, as changes have been dem onstrated in the Wilki ns, Baltim ore, 1989, pp 51-84 amount and distributioL1 of basement membra ne components [34]. 17. Parakka_l PF: U ltrastructura l changes of basemcnt mcmbrane durin g the hair In summary, these in vestigations in to the comparative ultrastruc­ growth cycle.) Cell mol 40:561-564, 1969 ture of norm al human anagen hair-follicle bulbs have produced 18. Parakkal PF: Morphogenesis of the hair fo llicle during catagen. Z Zd!forsch 107:174-186. 1970 some interesting fi ndings. Altho ugh fo llicles showed some marked 19. Sugiyam:1 S, Takahashi M. Karui m ura M: T hc ul trastructurc of hail' fo Ui cJes in sinlilarities in the CTE], there were also clear differences both on earl y nnd late catagcl1, with special refere nce to thc alteration of the j Ull ctional the outside of the follicle and around the derm al papill a as structure between the dermal papilla and the epitheli al components. ) UII,.n_ compared with the similar junction in skin. In particul ar, neither st/"llct nes 54:358-373, 1975 20. O li ver R I': T he dermal papill a and the development and growth of hair. ) Soc hemidesmosomes nor tonofilaments, as seen in the DE], were Coslll el Chelll 22:74 1-755, 1971 observed in any hair-follicle j unctions. Anchoring fi brils appeared 2 1. Oliver ItF. Jahodn CAll: T he dermal papilla nnd mail1 tcn:1I1 cc ofha_ir growth. In : well organized and in tercOlmected with extracellular matrix coll a­ Rogers GE, Reis PR, Ward KA, Marshall R.C (cds.). T//C Biology oj Wool alld gen in the dermal papilla, but no anchoring fi brils were detected at H air. C hapman & H aJI , Londo n, 1989. pp 59-61 22. R andn ll V A, T horn ton MJ. Ham,lda K, Messcnger AG: Mechanism ofandl' ogcl1 the junction on the outside of the follicle. T he lack of complexity action in cultured dermal papill a cell s dcri ved from humnn hair follicles w ith of the junctions in the hair follicle as compared w ith the similar varyin g rcsponses to androgens ill "h,o. J 111 vest De,.", atol 98:865-91 S, '1992 junction between dermis 3l1d is consisten t with the need 23. Lcwis PR.. Knight OP: Staining methods for scctioned matcrial. 1n: Ginuert AM for motility of fo llicular tissues, in contrast to the relatively (cd.). Practicnl Metllorls ill Electroll Microscopy, Vo l 5, Pal't 1. North- Holl and Elsevier, Amsterdam , 1977. PI' 40-53 permanent relation between basal epithelial cell s and the basement 24. Richardson KC. J anet L, Finke EH: Embedding in cpo,,), resins for ultrathin membrane. It will be in teresting to examine the ultras tructure of sectioning in electron microscopy. Sin ill Tee/lll ol 35:3 13-323, 1960 the important DPE] in hair follicles from patients with hair diseases, 25. Hardy MH, Van Exan [\I, 50nstegard KS , Sweeny PR: Basal lamina changes such as alopecia areata, to see w hether it is al tered in any way. during tissue in tc r ~ctio n s in hair faHjdes-nll itl 11itro ~ tu dy of norm al den nal papiUac and vita min A-induced glandul a_r morphogcnesis. J fllIICS t DCI'II/fllol 80:27-34, 1983 26. Mutasim OF, Takah ashi Y, Labib R S. Anhat GJ . Patel H I', Diaz LA: A pool of We 1V01lid like to thallk Dr. S. Macdoll ald Hil I/ all d Professor W J. Cllllliffe, bull o us pemphi goid antigen(s) is intracell ular and associated with the basal cell cytoskeleton-hcmidesrnosom e complex. ) III IIest Del'lII atol 84:47-53, 1985 Depflltll/eut of Del'llt alology, The Gmeral [llfirll/ ary, Leeds, alld Mr. D. Shat1)e, 27. Messenger AG, Elliott K, Temple A, Randall VA: Expression of basclllent Mr. M. T ill/ llt olls, all d col/eaglles of Ih e Plastic SlIrge/)1 alld BlIl'lls Ullit, Depar/II/ elll mcmbranc protein s and in terstitial c.::o l.! ;lgcns in derm;,1 papillae of hUl11 il ll Il air of Bioll/ edical Scieuces, Ullillers it)' of Bradford for fJrov idillg sa ll/ples of skill. We fo llicles.) III IIest Del'lII atol 96:93-97, 1991 ackllollliedge ti,e expert /ecJl/l ical assis/allce tIIill, II/ icrodissectio ll of I/O irfo llicles of Dr. 28. Wcstgate GE, Shaw OA, 1-I ~l rr ap GJ, Couclullan JR : ImmunohistochcHlical locali zation of bascment membrane componcll ts duri ng hair folliclc morpho_ MJ. Tllomtoll, Depfll1/11ml of Bioll/edical Sciellces, Ulliversil), of Bradford. genesis. ) IlIvcst Derlll alol 82:259-264, 1984 2Q. Bard S, Macouin C, T h.i volct J, Sen gel P: Heterogeneous distribution of bullo us pemphigoid antigcn during hair devclopmc nt in the mouse. Arch A ll at Nlicrosco fJ REFEREN CES Exp 70:'141-148, 1981 30. Uno H: Biology of hair growth. Selll ill ReJll"od ElldoC/ill ol 412:131-141, 1986 1. Briggaman RA, Wheeler CEo The epidermal-dermal junction. J fl lIIest Dermatol 31. Montagna W, Pa rakkal PF: T he pil ary apparatus. In : Montagna W, I'arakkal P 65:71-84,1975 (cds.). Til e Strllclll re alld F' IIICtio ll ~r Skill . Academic Press, London, 1974, PI' 2. Briggaman R.A: Basement membrane formation and origin with special reference 172-258 to skin. From Malrix Bioi 9:142-154, 1981 32. Reynolds AJ , Jahoda CAB: Inductive properties of hair follicle cells. AII II NY 3. Tidman MJ , Eady RAJ: Ultrastructural morphometry of norm al human dermal­ Acnd Sci 642:226-242, 1991 epidermal junction: the influence of age, sex and body region on laluin ar and 33. Shjmi zu Ii, Ishida-Ymnarn oto A, Ea dy RAJ: T he usc of si lver cnhan ccd I tUn non laminar components. ) b lllest Dem/(/lol 83:448-453, 1984 gold probcs for li ght ,m d electron-microscopic locali zOitio ll of in tra ccllubr and 4. Ea dy RAJ: Bascmcnt mCl11branc-interf.1cc bctwecn the epithe lium an d the extracell ular antigens in skin. ) H islochelll C ytochelll 40:883-888, 1992 dermis: structural features. Arcll Demrato/124:709-7l2, 1988 34. Couchman JR, Gibson WT: Exprcssion of bascmcnt membra ne components 5. Briggaman RA, DaUdorf FG, Wheeler CEo Formation and origin of ba sal lamina through morphologica l changes in the hair growth cycle. Dell Bioi 108:290- and anchoring fibrils in adul t human skin. ) Cell BioI 51 :384-394, 1971 298, 1985