The Golgi Element in the Cells of the Firstand Second Convoluted Tubules of the Cat Kidney.

Transcription

1 The Golgi Element in the Cells of the Firstand Second Convoluted Tubules of the Cat Kidney. By J. F. A. McManus, Major, R.C.A.M.C. With 5 Text-figures. CONTENTS. PREFACE 97 LITERATURE 97 MATERIALS AND METHODS RESULTS 99 DISCUSSION SUMMARY AND CONCLUSIONS REFERENCES APPENDIX: TECHNIQUES USED PREFACE. PREVIOUS descriptions of the Golgi element in the kidney tubules have been largely restricted to smaller animals the frog, the mouse, the rat, &c. In addition Eamon-y-Cajal has illustrated his conception of these structures as shown in the rabbit by the urano-formol technique, but the actual descriptions are rather sketchy. Since the experimental study of kidney disease has made use of larger mammals the cat, rabbit, and dog it was thought worth while to investigate the appearances of the Golgi element in the kidneys of some of these animals in their normal condition as a necessary preliminary to a cytological review of experimental nephritis which will be undertaken when circumstances permit. These studies were begun also in the hope of demonstrating some peculiar feature for the macula densa, in which respect the results have already been described briefly (McManus, 1943). LITERATURE. It is not proposed to enter into a comprehensive and detailed review of the various publications describing the Golgi element in the kidney Emmet (1938) has done this. In general, NO. 337 H

2 98 J. F. A. MCMANUS structures have been described as being of a granular or netlike nature. Their position in the tubule cell has been pointed out as being on the lumen side of the nucleus. Fischer (1938) has described a cycle of activity in which the Golgi element traverses the cell as a feature of induced diuresis in the rat. A. - { 1 f:\ ' ' _ ' /?:i A f :^> i Text-fig. 1. Ramon-y-Cajal's illustrations of the Golgi structures in the tubules of the kidney of the young rabbit. Reference in text. Eamon-y-Cajal's illustration of the Golgi element in the kidneys of the young rabbit (Text-fig. 1) shows structures comparable to those described in the lower animals. The text, accompanying the illustration, states:'... investigations prove that in the resting phase the cells of the convoluted tubes contain a diminutive apparatus of Golgi (Text-fig. 1B) which is progressively developed and elongated as the large excretory tubes are approached. Granular and rudimentary in the tubes of Henle (A), it forms in the convoluted tubules a group of anastomatic loops while in the straight excretory tubes it forms a net of longitudinal trabeculae (D).'

3 GOLGI ELEMEKT IN TUBULES OF THE CAT KIDNEY 99 MATEEIALS AND METHODS. Young kittens and older cats were killed rapidly by ether. The kidneys were immediately removed and small blocks, about 2x3x3 mm., were placed in the appropriate fixatives. Some details of technique are mentioned in the appendix to this paper. Both silver impregnation and osmification techniques were used (Da Pano, Aoyama, Weigl, and Kolatchev). Complete failure of demonstration of the Golgi element in the cat kidney followed all our osmium tetroxide techniques although the dorsal root ganglion, used as control material, showed perfect impregnation of the Golgi body. The silver techniques were more satisfactory. Da Pano's and Aoyama's methods were used interchangeably with the latter, having the advantage of being more rapid. In neither the Da Pano nor the Aoyama method did it seem as if the histological details were very well preserved, although it is possible that dehydration methods might be altered to improve this or that celloidin imbedding might be preferable to the paraffin which was employed. RESULTS. In most instances all or part of the individual block showed material in the cells which corresponded to Golgi element in size and position. These structures were usually well shown in the proximal tubules and in the loops of. Henle, but their appearance in the distal tubule was more difficult to make out because of a diffuse brown staining which was frequently a feature of the cytoplasm of the cells. Toning of the sections in gold chloride, as detailed in the appendix, helped considerably in the demonstration of the Golgi element in this area, but tended as a rule to diminish further the quality of the histological picture. In the descriptions which follow 'First Convoluted' and 'Proximal' tubule are used interchangeably, as are 'Second Convoluted' and 'Distal' tubule. In llie low magnifications the Golgi element has the appearance of a rod or bar and, in the animals killed in the manner

4 100 J. F. A. MCMANUS described, it is situated immediately on the lumen side of the nucleus. We have made no special study of the collecting tubules, the glomerulus or vessels, or of the loops of Henle; and our investigations have been restricted to the first and second convoluted tubules. S. I n IS 4 Text-fig. 2. Golgi element, first convoluted (proximal) tubule cell of cat kidney. Da Fano method. Photomicrograph ocular magnification, x 950, further enlarged. Text-fig. 3. Golgi element, second convoluted tubule cells of cat kidney. Da Fano method. Photomicrograph, x 1200 (J. R. B.). Text-fig. 4. Golgi element, macula densa of cat kidney, as Fig. 3. (J. It. B.) O, Golgi body; I, lumen of renal tubule; n, nucleus. Text-figs. 3a and 4a are simplified copies to explain the photomicrographs Figs. 3 and 4. In all the first tubules of the younger animals and in the older animals, in those portions of the proximal tubules which are not infiltrated with fat, the Golgi element has the form which is shown in Text-fig. 2. Each appears as a small, slightly crescentic structure with a width approximately equal to the

5 GOLGI ELEMENT IN TUBULES OF THE CAT KIDNEY 101 longer axis of the nucleus, and about one-third of this size in the other dimensions. It is not net-like in appearance when the impregnation has been sufficient, but appears rather as a solid, slightly irregular structure. The infiltration of a portion of the proximal tubule with fat, which occurs in the adult cat, results in a dispersion of the Golgi element as fine particles throughout the cell. '. fa//,- ;.. I. - * r. y " '/ Text-fig. 5. Juxta-glomerular (or Glomerular) complex, from McManus, Relationships at root of glomerulus. A, macula densa, in wall of distal tubule. B, afibrillar cells, in efferent arteriole. In the second (distal) tubule the appearance is very much the same as that shown in the normal proximal tubule cells with a slight decrease in all the dimensions of the Golgi element noticeable (Text-fig. 3), with perhaps some greater granularity and a concentration of its material so that it appears to be more deeply impregnated. This is a fortunate feature because of the deeper staining of the tubule cells. The position of the Golgi element in the cells of the distal tubule is the same, with exception of one area, as that in the cells of the proximal tubule; it is on the lumen or free side of the nucleus. Zimmerman (1938). described as the 'Macula Densa' an aggregation of the cells of the second convoluted tubule at the po^nt where the tubule is most closely applied to the glomerular rooi in the angle between the afferent and efferent arterioles. As we previously pointed out in a short note (McManus, 1943),

6 102 J. F. A. MCMANUS the Golgi element of the cells composing the macula densa is situated (Text-fig. 4) on the basal side of the nucleus, that is in apparent reversal to the position of the Golgi element in all of the proximal tubules and in the rest of the distal tubules. It is of interest to note that, both in the kidney of the young rabbit and in one human case of nephritis, sections from the kidneys stained by the silver techniques described showed reversal of the Golgi element in the macula densa, identical with that found in the cat. DISCUSSION. Several features appear to arise from this study. The first concerns the structure of the Golgi element in the kidney tubule cells, while the second feature indicates a unique condition obtaining in the cells of the macula densa. Where impregnation has been sufficient the Golgi element in the proximal and distal tubule appears as a solid structure, as shown in Text-figs. 2 and 3. This is hardly the result of overimpregnation since the reticulin of the kidney, which ordinarily takes up any superfluity of silver, shows no staining. Only the surface of the mass of the chemical substances appears to be stained rather than a diffuse stain of the whole body of the Golgi element. Here again the possible function of the Golgi element as an absorptive surface for the transmission of material across the cell is suggested in Text-fig. 2 in which a small globule can be seen outside the Golgi proper but attached to it. The apparent reversal of the Golgi element at the resting state in the cells of the macula densa suggests that these cells differ from the other cells of the renal tubules. The difference may be hypothesized from the customary position of the Golgi element on the side of the cell to which secretion is directed, to consist in the cells of the macula densa abstracting some material from the contents of the second convoluted tubule and transmitting this material to the cells of the arterioles at the glomerular root. It is worth while to mention that Euyter (1925) pointed out the afibrillar condition of the juxta-glomerular cells forming the

7 GOLGI ELEMENT IN TUBULES OF THE CAT KIDNEY 103 arteriolar walls in the kidneys of the mouse, and that identical cells in the corresponding position have been described in every species studied including the human (McManus, 1942). We have pointed out that the macula densa and the specialized sequents of the arterioles make up a functioning unit, for which we proposed the term of 'juxta-glomerular complex', and this reversal of the Golgi element in the cells of the macula densa gives some hint as to the manner by which the unit is integrated. Extending the hypothesis to its logical conclusions one may suppose that the conditions in the distal tubule control, by means of the macula densa transmitting some substance to the special arteriolar cells at the glomerular root, the hydrostatic adjustments in the blood supply to the nephron. This theory (resembling that which was first outlined by Goormaghtigh (1987) though without cytological evidence for its possibility) is suggested as a working basis for the investigation of the normal and diseased kidney. Added force is given to the possibility of the reversal of Golgi element in the cells of the macula densa having something to do with the working of the nephron by the fact that the maculae densae which go to make up the juxtaglomerular complexes of the glomeruli in the proliferating subcapsular zone of the kidney of the very young kitten do not show the reversal of position for the Golgi element in their cells. This reversal seems to be attained only by the more adult structures in the kitten, in the deeper portions of the cortex. SUMMARY AND CONCLUSIONS. 1. The Golgi element in the cells of the first and second convoluted tubules, of the cat kidney have been demonstrated by the Aoyama and Da Fano techniques. 2. In both sorts of tubules the Golgi element appears as a rod-like or granular, sometimes crescentic structure, solid rather than reticular. The Golgi element usually lies on the free side of the nucleus. 3. In the macula densa of the second convoluted or distal tubule the Golgi element is seen on the basal side of the nucleus, that is, in apparent reversal to the position in the other cells. This condition in the cat is similar to that which is found

8 104 J. F. A. MCMANUS in the rabbit and has been found in one autopsied case of nephritis (human). 4. The reversal of the Golgi element in the cells of the macula densa suggests (a) that some substance from the contents of the tubule here passes across the cells of the distal tubule to the specialized cells at the glomerular root, (6) this process is the method by which the haemodynamics of the nephron are integrated. This proposal, much like that made by Goormaghtigh, is here suggested as a basis upon which physiology of the normal and diseased kidney might be investigated cytologically. [REFERENCES. Emmet, 'Anat. Record', 70. Fischer, 'Ztschr. Micr. Anat. Forsch.', 43. Friedman and Kaplan, ' Journ. Exp. Med.', 76. Goormaghtigh, 'C.R. Soc. Biol., Paris', 124. McManus, 'Lancet', 'Nature', 152. Ramon-y-Cajal, ' Histology' (text). Bailliere, Tindall & Cox, London. Ruyter, 'Z. Zellforseh.', 2. Zimmerman, 'Ztschr. Mikr. Anat. Forsch.', 32. APPENDIX. Techniques used in the Study of the Golgi Element of the Kidneys. The cat kidneys were removed immediately after the animal had been asphyxiated by commercial ether. The two rabbits studied were killed each by a simple blow on the head. The human kidneys were removed at autopsy one. hour after death from a systemic infection. Small blocks were cut each about 2x3x3 mm. and several blocks placed in each of the various fixatives. In the rabbit kidneys-da Pano's technique was not used; in the human kidneys the osmium techniques were not used since their lack of value had by that time become apparent. Occasionally in the silver preparations the Golgi elements in the distal tubule could be seen but were obscured by the diffuse staining of the cytoplasm. In these cases after the sections were cut and mounted on the slides, sections were

9 GOLGI ELEMENT IN TUBULES OF THE CAT KIDNEY 105 brought through xylene and graded alcohols to water. After being rinsed in distilled water the sections were placed in 0-1 per cent, gold chloride, containing 3-4 drops of glacial acetic acid, for five to ten minutes. In the first few minutes the background loses much of its staining and the Golgi elements lose some of their clarity but longer toning appears to reinforce the impregnation of the Golgi without adding at all to the staining of the cytoplasm. This extra handling of the sections appears, unfortunately, to diminish further the preservation of histological detail. These studies would have been impossible without the advice, help, and encouragement of Dr. John E. Baker of the Department of Zoology and Comparative Anatomy, Oxford. Through Dr. Baker's kindness and that of Professor E. S. Goodrich, it was possible to confirm some of this work in their department. The technical assistance of S/Sgt. H. L. Mitchell, E.C.A.M.C., and the photographic ability of S/Sgt. M. S. Smith must be acknowledged, since the spare time of these N.C.O.s was freely given to helping in this work. Additional photomicrographs, as indicated, were taken by Dr. Baker. No. 8 Cdn. General Hospital, Cdn. Army, England. NO. 337