Scanning Electron Microscopy

Volume 1986 Number 1 Part I Article 28

4-18-1986

Scanning Electron Microscopic Studies on Microvascular Architecture of Human Coronary Vessels by Corrosion Casts: Normal and Focal Necrosis

T. Ono Kure Kyosai Hospital

Y. Shimohara Kure Kyosai Hospital

K. Okada Kure Kyosai Hospital

S. Irino Kagawa Medical School

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Recommended Citation Ono, T.; Shimohara, Y.; Okada, K.; and Irino, S. (1986) "Scanning Electron Microscopic Studies on Microvascular Architecture of Human Coronary Vessels by Corrosion Casts: Normal and Focal Necrosis," Scanning Electron Microscopy: Vol. 1986 : No. 1 , Article 28. Available at: https://digitalcommons.usu.edu/electron/vol1986/iss1/28

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SCANNING ELECTRON MICROSCOPIC STUDIES ON MICROVASCULAR ARCHITECTURE OF HUMAN CORONARY VESSELS BY CORROSION CASTS: NORMAL AND FOCAL NECROSIS

T. Ono ,§ Y. Shimohara , K. Okada , S. Irino *

Federation of National Public Service and Affiliated Perso nal Mutual Aid Assoc iation Kure Kyosa i Ho spital , Hiro shima , Japan *Th e First Departm ent of Internal Med ic ine, Kagawa Medi ca l School, Japan

(Re ce ived for public ation J a nuary 24, 1986, and in revis e d form April 18, 1986)

Abstract Introduction

Microvasc ular arc hitectur e of the norm al human hea rt and The morpholo gy of the coronary blood vessels of the heart myocardi al focal necros is were studied by sca nning electron has been extensiv ely investigated by variou s method s, includin g micro sco py of corrosion cas ts. Casts macrosco picall y identical dissection , dye injection , serial dissection, roentgenography , in­ in form to the left ventr icular posterior wall were prepared. jection corrosi on, plastic cast and their combi nation s. (2 ,3,6,7,10, The following results were ob tained in the norm al human 12, 16,18-20) Th ese studi es have bee n primarily focussed on the hea rt. (I) Mo st of the arteri oles co mmuni ca ted with ca pillar y arran ge ment and appearanc e of relatively large branches and plexuses smoo thly and strai ghtforward ly in the left ventricular on the genera l distribution pattern of myocardial capillaries , but posterior free wall. (2) Arterioles which branched from the hardly any reports have been mad e on the detailed arrangement arteri es ran in various directions and co ntinued into ca pillari es or distribution of the capill ar ies in the normal and abnorm al either at right angles or obliqu ely in the trab ec ulae ca rneae. (3) heart. capi llaries runnin g parallel with the cardiac muscle fibers ran Thi s paper describes our findings on the stereomicrovasc ular in different directions to cross over with each other in different arc hitect ure in the normal left ventri cular posterior wall of a layers of myocardium. Ca pill aries in the myocardium formed 24 yea r old Japanese female and foca l necros is in the heart of a co ntinu ous and coa rse net-like architec tur e with many bifur­ a 60 year old Japanese male obtain ed by sca nnin g elec tron cat ions and anas tomoses . Cap illaries were abo ut 5-7 µ.m in microscopy with the use of corros ion casts . diame ter. (4) Some veins gatheri ng cap illaries in the ep icardium ran into the myocardium and the others ran in the epicardi um . Materials and Methods Veins co nnecting with capi llari es in the myocard ium ran in the myocardial layer and co mmuni ca ted with large r veins. (5)A n The posterior free wall of the left ventri cle of seven autopsy ar ter io-veno us anastomos is and two different types of venous­ cases was removed together with a part of the ventri cular sep­ venous anastomoses were observed in the left ventricular pos­ tum and right ventri cular free wall at time of autopsy. terior wall. A teflon sheath needle was inser ted into the left circumflex At the site of foca l necros is, cross sect ions of dilated vesse ls branch of the coro nary artery , which was irrigated thoro ughly were observed in large numbers by light microscopy and sca n­ with saline solution (1000ml). The cut ends of the relatively large ning electron microsco py. (I) At the site of focal necrosis , dilated coro nary vessels in the myoca rdium were closed with ties. Then, ca pillari es runnin g with tortu os ity were see n in large numb ers half polymerized methylmethacrylate res in prepar ed by Mura ­ by sca nnin g electron microscopy of co rro sion cas ts. (2) Wh en kami's method (13) was injected und er a press ure of 100- 150 co mpared with vesse ls in the normal myocardium , small arter ial cmH20 until the coro nary vessels were filled with the injected branches were dilated and run tortuously. (3) These dilated resin. ca pillary plexuses were observed in the area which comm uni­ The resin injected hear t was immersed in hot water of 70°C cated with twigs bran ching off at the right angle from the arterial for 12- 24 h , macera ted for 10 h in hot bath (50 °C) of co ncen­ branch. trated sodium hydro xide solution , washed for 2 h in running water, and then dri ed in air. Key Words: Corro sion casts, scanning electron micro sco py, The co rrosion casts of the left ventricular posteri or wall thu s hum an coro nary vessels , microvasc ular architecture, focal prepar ed were trimmed into appropriat e blocks suitable for scan­ necros is. ning electron micro sco py (SEM), mounted on metal-stubs with

§Addre ss for correspondence: silver paint , coated by vaporiz ed gold , and observed with a T. On o JSM-24 type scanning electron microsc ope at an acce leratin g Federation of National Publi c Service voltage of 15kV. and Affiliated Personal Mutual Aid Assn . Kure Kyosai Hospital , Nishi Chuo 2-3-2 8 Kure City, Hiroshima Prefectur e, 737 Japan Phone No. (0823) 22-2111

263 T. Ono , et al.

Results of twigs, and that the myocardium of the ventricular wall and trabeculae carneae were filled with a capillary network. Vascular beds of the left ventricular posterior wall were suffi­ The following findings were observed by scanning electron ciently casted by injection of half polymerized methylmethacry­ microscopy of the corrosion casts. late resin (Figs. 1,2). It was macroscopically observed that coro­ Arteries nary arterial branches ran in the epicardium , giving off a number Comparatively large arteries with a caliber of 100- 150 µm

264 Microvascular Architecture of Human Coronary Vessels

Fig. l. The myocardium of the ventricular wall was filled 8). A relati vely large numb er of veins, co nnec ting with capil ­ with capillary network, and coronary arterial branches ran laries in the epicardium , ran and j oined w ith a large vein in in the epicardium. the epicardium (Fig. 9) , whil e oth ers ran into the myocardium from the epica rdium and connected with a large r vein having Fig. 2. Trabeculae carneae were also filled with capillary a caliber of about 85- 100 µm (Figs. 10, II) . Almo st all vein s, networks in the endocardium. co mmuni cating with capillary plexuses in the myocardium , ran and join ed with a larger vein in the myocardium (Fig. 12). Fig. 3. In the left ventricular wall, arterial branches (a) Anastomosed vessels divided into several arterioles which communicated with Th e arterio-venous ana stomos is in the subepica rdium of the capillary plexuses smoothly and straightforwardly. (Epicar­ left ventricul ar posterior wall was about 150 µm in diamet er dium of the left ventricular posterior wall). and co nnected also with capillar y plexuses (Fig. 13). A type of venous-venous anastomo ses with a calib er of about 30-75 µm Fig. 4. In the trabeculae carneae, the arterial branches (a) form ed a coarse net-lik e archit ectur e with som e ana stomo ses ran to the endocardium from the deep zone of the ventricular in the epicardium. Som e of the se anastomotic vesse ls conne cted wall and divided into several arterioles which continued into with capill ary plexuses in the epicardium and ran into the myo­ capillaries at right angles or obliquely. ca rdium (Fig . 14). Another typ e of venous-venous anastomo sis was observed in the myocardium of the left ventricular posterior Fig. 5. Comparatively large arteries (A) penetrated between wall. Thi s anastomos is form ed a loop and co nnected with veins the trabeculae carneae and the endocardium and gave off runnin g into the myocardium from the epica rdium (Fig. 15) . twigs, communicating with capillary plexuses. (Tr: trabecu­ Focal necrosis Iae carneae , Ed: endocardium) Many cross sec tions of dilated vesse ls we re observed in large numbers in foca l nec rosis areas by light microsco py (Fig. 16). Fig. 6. Capillaries in different layers (C 1, C2) of the myo­ Th e norm al myoca rdium has many mu sc le bundl es , while few cardium ran in different directions, crossing over each other. mu scle bundl es and dilated vesse ls were observed in areas of (The capillary plexus of deep zone is too deep to bring into focal necrosis by scannin g electron microsco py (Fig. 17). Dilated focus). ca pillaries and arterial bran ches, runnin g with tortu os ity, were observed in a site of focal nec rosis of the left ventri cular wall ran among the capill ary plexuses in almost a straight line, divid ­ by sca nnin g electron microscop y of the co rro sion cas ts (Figs. ed into severa l finer bran ches whil e runnin g almost para llel w ith 18, 19, 20) . Th ese dilat ed capill ary plexuses were obse rved in the ca pill ary network . Art erioles with a ca liber of 14-2 0 µ m the area communi cating with twigs which divided at a right angle co mmuni ca ted w ith ca pillar y plexuses smoothly and straight­ from the arterial branch (Figs . 2 1, 22). forwa rdly in the left ventri cular free wall (F ig. 3). Discussion The diameter of the vesse ls was almost the same as that seen in the norma l myocar dium in all cases. In the endoca rdial sur ­ Th e morph ology of the coro nary blood vesse ls of the hea rt face of the trabecu lae ca rneae , arte rial branc hes w ith a ca liber has bee n studied extensively by various method s. Rece ntly, the of about 20 µ m ran to the endoca rdium from the deep zone of microvasc ular architecture of coro nary blood vesse ls of the heart the left ventri cular free wall and divided into severa l twigs. Th ese has been observed by scanning electron microsco py (8, 13, 15- 17, arter ial bran ches co ntinu ed into capill aries either at right angles 22) , but little study has bee n made on the de tailed arrangement or obliqu ely (Fig. 4) . Compa ratively large arterial branches, of the microvasc ular architec tur e in the ventri cular wa ll of the which were about 70 µm in diameter, penetrat ed betwee n the hum an hear t. Thi s paper desc rib es the well defined findin gs of trabec ulae ca rneae and the endoca rdium of the left ventri cular the microvasc ular arc hitectur e in the ventri cular wa ll of the wall and gave off twigs which communi cated with capillary plex­ human heart observed by scannin g electron microsco py of casted uses (Fig. 5). sample with methylmethac rylate. Capillary plexuses Arterial bran ches divided into arter ioles , communi cating with It appea red that ca pill aries in the myoca rdium ran para llel ca pillary plexuses smoothly and straig htfo rwardly. Yokota et al. with the ca rdiac muscle fiber. Thus, capillaries in di fferent layers (24) have reported in their sca nnin g electro n microsco pic stud y of the myoca rdium ran in di fferent dir ections, cross ing over with of cas ted sa mpl e with Mercox that the d istance fro m the point eac h other (Fig. 6). co nnecting w ith capill aries to the point di vidin g the arterioles Comp ara tively large vesse ls w ith a ca liber of about 70 µm is short. In this study, variou s lengths of arterioles, which divided ran betwee n these differ ent layers. Capill aries in the myocar­ from arterial branch es and co nnected with capill ary plexuses , dium form ed a coa rse net-like archit ectur e with many bifur ca­ were observed . Arterial branch es divid ed into arterioles and con­ tions and anastomo ses (Fig . 7) . The di ameter of each capillar y nected with capillaries either at right angles or obliqu ely in the was measured to be about 5-7 µm , and the di stance betw ee n trabecul ae ca rneae. the capill aries was ab out 17- 30 µm . Capill ary plex uses in the Comparati vely large arteri al bran ches, whi ch have bee n re­ trabe culae ca rneae had the sam e architectur e as the left ventri ­ ported by Yokota et al. (24), were also obse rved in this stud y cul ar free wall. and these arterial branch es penetrated betwee n the trabe culae Veins ca rneae and the endoca rdium , and divided into tw igs comm uni­ Th e co nnec tions betwee n capill ary plexuses and veins we re cating with ca pillaries in the endoc ardium . Vesse ls opening into observed to be much more num erou s than those betwee n capil­ the ventricular cavity were not obse rved by scannin g electron larie s and arteriol es . Veins, gath erin g capill aries like bran ches microsco py with corro sion ca sts, but leaka ge of the fluid , when of a tree, were observed in the epicardium and myoca rdium (Fig . the co ron ary vess el s were irri gated , was ob se rved.

265 T. Ono , et al . . ~, . I

Fig. 7. The capillary plexuses with many bifurcations and Fig. 8. This vein (V), gathering capillaries, ran tortuously anastomoses formed a coarse net-like architecture in the in the myocardium. myocardium.

Fig. 9. Relatively large number of veins (V), gathering capil­ Fig. 10. Some veins (V) ran into the myocardium from the laries, ran in the epicardium and joined with larger veins. epicardium.

Capillarie s ran parallel with cardiac muscle fibers (8,9,14,15,16) been demonstrated by the scanning electron microscopic method . forming a coar se net-like architecture with many bifurcation s An arterio -venous anastomosis and two types of venous-venous and anastomose s. Thus, capillaries in different layers of the myo­ anastomoses , forming the coarse net-like architecture and loop , cardium ran in different directions, crossing over with each other. were observed in this study. The se findings are similar to those observed in the rabbit (8,16). Focal myocardial necrosi s is said to occur in the hearts of According to Shozawa et al. (22 ,23) and Kaneko et al. (11)," the various diseases. It was reported by Eng et al. (5) that a greater intramyocardial microva scular network can be subdivided into number of microspheres were present in the subendocardial three parts, arterial , capillary and venous sites;' but in this study layer, while necrotic lesions were more frequent in the mid­ a continuous capillary network , communicating with arteriole s wall and epicardial layers by experimental microsphere em­ and venules in various parts , was observed . bol ization . Shozawa et al. (22) have reported that the intramyo­ Some veins gathering capillaries in the epicardium ran into cardial microvascular network is subdivided into three parts , the myocardium and communicated with larger veins. To our arterial, capillary and venous sites , and focal necrosis has oc­ knowledge , findings of this nature have not yet been reported. curred only in the arterial site of the capillary network. In our Considerable variations in pattern of anastomosed vessels have observation , focal necrosis in the myocardium of aged human been reported by several researchers (1,4,21). These variations heart was observed in the areas connecting with twigs divided seem to be due to a difference in techniques and species used. from arterial branches at right angles. Dilated capillaries and Several patterns of anastomosed vessels of the animal heart have arterial branches with tortuosity were observed in sites of focal necrosis.

266 Microvascular Architecture of Human Coronary Vessels

Fig. 11. The veins, running into the myocardium from the epicardium, connected with larger veins (v) which joined with the largest vein (V) in the myocardium. (Capillary plex­ uses in the epicardium were removed. Some of cut ends of the veins connected with the veins which ran into the myo­ cardium from the epicardium.)

Fig. U. The veins, connecting with capillaries in the myo­ cardium, joined with larger veins (V) in the myocardium.

Fig. 13. An arterio-venous anastomosis in the subepicardium of the left ventricular posterior wall was about 150 µm in diameter. (A: artery, V: veins. The capillary plexuses around the anastomoses were removed.)

Fig. 14. Venous-venous anas­ tomoses formed a coarse net­ like architecture with some anastomoses in the left ven­ tricular posterior wall.

Fig. 15. In the myocardium of the left ventricular pos­ terior wall, a venous-venous anastomosis formed a loop, and connected with capillary plexuses and veins which ran into the myocardium from the epicardium. (V: veins, Capillary plexuses in the epi­ cardium were removed.)

267 T. Ono, et al.

Fig. 20. Dilated capillaries (C2), communicating with Fig. 21. These dilated capillary plexuses were observed in normal capillary plexuses (C1) were observed in the site of the area communicating with twig (arrow) which divided focal necrosis. at right angles from the arterial branch (a).

268 Microvascular Architecture of Human Coronary Vessels

Fig. 22. The twigs (arrows), dividing at right angles from the artery (A), connected into the dilated abnormal capillary plexuses (C2) with tortuosity. (C1: normal cap­ illary plexuses)

Fig. 16. Many dilated vessels were observed in areas of focal 11. Kaneko N, Takeishi M . Toyoda C, Hirosawa K . (1981). necrosis, while a few capillaries were observed in the nor­ Basic structure of microcirculatory system and capillary sinus mal myocardial layer. (light microscopy). in normal human heart . Jap. Circulation J. 45, 865. 12. Kugel MA. (1927). Anatomical studies on the coronary Fig. 17. In areas of focal necrosis fewer muscle bundles and arterie s and their branches . Am . Heart J. 3, 260-270. many dilated vessels were observed (arrows). 13. Murakami T. (1971). Application of scanning electron microscope to the study of the fine distribution of the blood Fig. 18. Dilated capillaries (C2) and arterial branches (a) vessels . Arch . Histol. Jap. 32, 445-454. were running with tortuosity in the site of focal necrosis 14. Ono T, Shimohara Y, Okada K, Irino S. (1981).Scanning (C1: normal capillary plexuses) electron microscope studies of the coronary microvascular archi­ tecture by corrosion casts. J. Jap. C. Angiology, 21(4), 269-m. Fig. 19. In the site of focal necrosis, dilated capillaries (C2) 15. Ono T, Shimohara Y, Okada K, Irino S. (1982). Scan­ ran tortuously and formed coarse net-like architecture. (a: ning electron microscope studies of the coronary microvascular arterial branch, C1: normal capillary plexuses) architecture in the ventricular septum and right ventricular free 4 wall by corrosion casts. J. Jap. C. Angiology, 22(5), 303-311. 16. Petelenz T. (1965). Radiological picture of extra-coronary arterie s of myocardium in man. Cardiologia , 46, 65-78. References 17. Phillips SJ, Rosenberg A, Meir-Levi D, Pappas E. (1979). Visualization of the coronary microvascular bed by light and 1. Bloor CM, Leibow AA. (1965). Coronary collateral cir­ scanning electron microscopy and X-ray in the mammalian heart. culation . Am . J. Cardiol. 16, 238. Scanning Electron Microsc. 1979; III: 735-742. 2. Brown RE . (1965). The pattern of the microcirculatory 18. Pina JAE, Correia M, O'Neil JG, Rendas AB. (1981). Mor­ bed in the ventricular myocardium of domestic mammals . Am . phology of the veins draining the coronary sinus of the dog. J. Anat . 116, 355-374. Acta Anat. 109, 122-128. 3. Clarke JA. (1965). An X-ray microscopic study of the ar­ 19. Rodriguez FL, Robbins SL. (1965). Post mortem angio­ terial supply to the conducting system of the human heart . Brit. graphic studies on the coronary arterial circulation. Am . Heart Heart J. 27, 879-883. J. 70, 348- 364. 4. Eckstein RW. (1954). Coronary interarterial anastomosis 20. Schlesinger MJ, Zoll DM, Wessler S. (1949). The conus in young pigs and mongrel dogs. Circulation Res. 2, 460. artery. A third coronary artery. Am . Heart J. 83, 823-836 . 5. Eng C, Sho S, Factor SM , Sonnenblick EH , Kirk ES. 21. Sheldon WC. (1969). On the significance of coronary col­ (1984). Myocardial micronecrosis produced by microsphere em­ laterals . Am. J. Cardiol. 24, 303. bolization . Circulation Res. 54, 74-82 . 22. Shozawa T, Kawamura K, Okada E, Ono Y, Kadowaki 6. Estes Jr EH, Entman ML, Dixon HB, Hackee DB, Durham K, Yoshida K. (1980). The focal fibrosis of the bundle bran­ NC. (1966). The vascular supply of the ventricular wall. Am. ches of the conduction system and the myocardium especially Heart J. 71, 58-67 . on the basis of an anatomical study of micro circulatory archi­ 7. Farrer-Brown G. (1968). Normal and diseased vascular pat­ tecture . Akita J. Med. 6, 279-291. tern of human heart. Brit . Heart J. 30, 527-536. 23. Shozawa T, Kawamura K, Okada E. (1981). Study of intra­ 8. Irino S, Ono T, Shimohara Y. (1982). Microvascular archi­ myocardial microangio architecture with respect to pathogenesis tecture of the rabbit ventricular walls: A scanning electron of focal myocardial necrosis. Bibliotheca Anat. 20, 511-516. microscopic study of corrosion cast. Scanning Electron Microsc. 24. Yokota K, Sito N, Abe M , Kosato Y, Takagi K, Yamashita 1982; IV: 1785-1792. M . Ishikawa E, Kaneko Y, Kato S, Tokutomi M. (1983). Scan­ 9. Izumi T, Shibata A, Fukuda J. (1982). Demonstration of ning electron microscope studies of the coronary microvascular small blood vessels in human cardiac muscle under the scanning architecture in the myocardium in human heart by corrosion electron microscope. J. Clin. Electron Microscopy, 15, 293-303 . cast. J. Jap. C. Angiology. 23(6), 643. 10. James TN . (1965). Anatomy of the coronary arteries in health and disease. Circulation , 32, 1020-1033.

269 T. Ono, et al.

Discussion with Reviewers A. Lametschwandtner: Interestingly in the area of focal necrosis you convincingly could demonstrate dilated capillaries. A.C. Nelson: Apparently, the tissue preparation did not involve The same observation is reported to occur in the capillary bed fixation nor was the tissue likely to be fresh. Were there any of skeletal muscle neighboring a malignant skin tumor in labora­ problems in casting that may have resulted from tissue distor­ tory mice (Grunt et al., 1986). Could you comment upon the tion or rupture or from clotted vessels? cause of capillary dilatation? Authors: The heart was contracted by heating for polymeriza­ Authors: The cause of capillary dilatation was unknown. In tion, therefore the corrosion casts, in the dilated states of vessels our studies, the dilated capillaries were found in the peri-infarc­ in the contracted myocardium, were observed in this study. Rup­ tion area of the human and the rabbit heart. Probably, the dilated ture of vessels was observed in some spots. capillaries were observed in the damaged myocardium or skeletal muscle which resulted from anoxia and others. A.C. Nelson: The authors have observed dilated capillaries in the region of necrosis. What is the origin of these dilated vessels? A. Castenholz: Did you also examine stained sections in the Since necrosis results from reduced vascular perfusion which light microscope which can give information about the struc­ leads to tissue death, why does the necrosis appear to be heavily tural situation of the vascular wall so that a more exact classifica­ vascularized with dilated vessels? This seems counter intuitive. tion of the vascular corrosion casts with regard to capillaries, Authors: The origin of the dilated capillaries was unknown. arteriolar and venous vessels as well as small arteries and veins It was obscure that the dilated capillaries were made with the was possible? decrease of myocardium after necrosis or with the view of hype­ Authors: The light microscopical observation was not done. remia for restoration. These dilated capillary plexuses were In the SEM observation of corrosion casts and tissues, arteries observed in the area which communicated with the twigs branch­ ran in straight lines and veins showed slight tortuosity. On the ed at right angles from the arteries, therefore it was supposed, surface of artery, longitudinal groove-like indentations were anoxia was repeated under various states in life. observed . The surface of vein showed round to oval depressions probably made by the lining endothelial cell nuclei. A. Lametschwandtner: Could you please comment on the per­ fusion pressure you used to clean the circulatory system of the A. Castenholz: In the discussion you mention that, "a leakage excised left posterior wall of the autopsy-heart free of blood? of the fluid, when the coronary vessels were irrigated, was ob­ Did you use thrombolytic agents in the rinsing solution? served." Has this phenomenon preferably been observed on the Authors: Thrombolytic agents were not used. Saline solution venous side of the capillary bed in the normal myocardium or was injected under pressure of about 100-200 cmH20 to clean in the dilated vessels appearing in the necrotic region? It might the circulatory system, and saline solution (10-20ml) sometimes then indicate an increased permeability or fragility respective­ injected manually within 5-10 sec. ly in these vascular areas. Authors: In the macroscopical observation, a leakage of the A. Lametschwandtner: How did you trim the casts to blocks fluid was observed behind the trabeculae carneae of the nor­ of appropriate sizes? mal heart and also the pathological heart with focal necrosis. Authors: The casts were cut and trimmed with a knife and a In this SEM observation, a leakage of the resin was not found. pair of scissors. S.J. Phillips: The authors show a SEM viewed area of focal A. Lametschwandtner: When referring to the veins draining necrosis. Where in the wall thickness was this lesion seen? the capillaries of the epi-and myocardial layers of the heart you Authors: Focal necrosis area was seen in the endocardial side referred to them as, "gathering capillaries like branches of a tree." of the myocardium. Do you mean that these veins are the so-called turnip-root-veins described by Brown (1965)? What is the situation in the endo­ S.J. Phillips: Figure 19 shows in places a state similar to that cardium? we showed in the contracture-state cat heart. Would the authors Authors: The veins observed in this study were probably the comment on this similarity? same as the so-called turnip-root-veins, but the veins were not Authors: The abnormal arterial branches and the dilated as thick as turnip-root and like branches of a tree in the human capillary plexuses were also observed around the myocard infarct heart. In this study, the vein gathering capillaries in the endo­ of the rabbit and the human heart. Probably, these abnormal cardium was not observed. vessels could be found in the damaged myocardium which result from anoxia. A. Lametschwandtner: There is a still lasting debate on the nature of Thebesian veins of the heart. Would you please com­ ment upon your failure to demonstrate these veins in your mate­ rial? Authors: In the macroscopical observation, a leakage of the saline solution was observed behind the trabeculae carneae. Additional Reference Thebesian veins probably extend into the left ventricular cavity 25. Grunt TW, Lametschwandtner A, Karver K, Staindl 0. behind the trabeculae carneae, therefore it was very difficult (1986). The angioarchitecture of the Lewis lung carcinoma in that the Thebesian veins were observed by scanning electron laboratory mice: A LM and SEM study. Scanning Electron microscopy with the use of corrosion casts. Microsc . 1986; in press.

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