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THE GLOMERULUS IN ACUTE NEPHRITIS.

It might be thought that in such a common condition as acute nephritis, all that there was to observe microscopically would have been described long since. Better methods of technique and more accurate observations, as well as advance in knowledge as to the nature and development of cells, however, render it essential for us to revise our opinions upon the most ordinary of subjects from time to time.

The glomerulus of the kidney has always been somewhat of a puzzle, both to the normal and to the morbid histologist. The exact nature of the epithelial cells covering it, and of those lining Bowman's capsule—the question as to whether or not it contains cells of a connective tissue origin—as well as the function of the structure itself, have occupied the attention of observers for many years. Intimately bound up with the structure and function of any particular tissue, as well as with the question of the changes which the tissue undergoes under pathological conditions, is the developmental history of the cells which compose it. Much has been done on the question of the development of the glomerulus from the time of Remak onwards. More recently Hamburger, Bornhaupt, and Ribbert have turned their attention to the question, but none have done more to elucidate the early stages in the process than Herring (Journal of Path. and Bact., July, 1900). The conclusions of the last-named author may be summed up thus :—The kidney arises from two distinct structures, viz., the kidney blastema and the ureter. The former is of mesoblastic origin, and consists of a mass of cells closely related to the blastema of the Wolffian body. From the kidney blastema arise the Malpighian bodies, convoluted tubules, the connective tissue framework, and capsule. Each Malpighian body, with its tubule, arises as a solid mass of cells at the periphery of a lobule, either under the capsule or in the inter-lobular septa, in close relation to the dilated extremity of a ureter branch or collecting tubule. The solid cell mass acquires a lumen, and takes on

the shape of an S. The lower limb of the S becomes a Malpighian body, the upper and middle limbs form convoluted tubules, the bend between them constituting Henle's loop, while the extremity of the upper limb joins the collecting tubule and forms the greater part of the junctional tubule. The Malpighian body forms in the lower limb of the S-shaped tubule, and is the first part to show differentiation.' A splitlike lumen appears early, and attains considerable size. The convex side of the limb develops into the epithelium which lines Bowman's capsule, the concave side into the epithelium which covers the glomerulus. The epithelium on both sides is similar at first, but only for a very short time; the cells lining the capsule becoming thin and flattened.

The glomerulus is formed, not by an invagination, as many still suppose, but by a thickening of the epithelium. The capillaries of the glomerulus develop in situ, and are covered by the epithelium. The division of the glomerulus into lobes comes about by the penetration of the epithelial cells between the capillary loops. When the glomerulus is fully formed, the cells diminish in size, and become flattened like the cells lining the true capsule.

According to Herring, the glomerulus contains, in addition to endothelial and epithelial cells, cells of a connective tissue nature. This is denied by Fichera and Scaffidi. The homogeneous basement membrane of Bowman's capsule does not exist during the process of development. The cavity of Bowman's capsule may be regarded as of a nature similar to the peritoneal cavity, and the cells which line it as analogous to the endothelium of the peritoneum. That the cells covering the glomerulus have a secretory function is possible, especially as they are so closely related to the epithelium of the convoluted tubules developmentallò.

Turning now to the bearing of these developmental facts upon inflammatory lesions of the kidney, we find the most recent views well summarised in a paper by Fichera and Scaffidi (Virchow's Archiv., 1904, Bd. 177, p. 63). These authors are in agreement with Herring on most developmental points except in this : that they deny the presence of

cells of a connective tissue nature within the glomerulus itself. Their conclusions are the result of an investigation into eight cases showing various degrees of glomerulonephritis. They distinguish three main varieties, viz., desquamative, proliferative, and hæmorrhagic.

The first important change noted is in the basement membrane, which shows thickening and fibrillation. In the gaps between the fibrils appear wandering cells. The structure shows a remarkable persistance, and remains after all epithelium has been desquamated. As previously mentioned, it only lines Bowman's capsule, and is not continued on to the glomerulus itself, at any rate in adult life.

The second change mentioned is a desquamation of the epithelium covering the glomerulus and lining the capsule. The process usually commences with a swelling of the cells, which become cubical in the case of the cells lining the capsule, and club-shaped in the case of the cells covering the capillary tuft. The cell protoplasm becomes granular and vacuolated, and the nuclei show caryolysis and caryorrhexis. Later, the cells become desquamated, and lie in the space along with leucocytes and the debris of red blood cells. After being thrown off in this way, the cells show all stages of degeneration up to complete disappearance. Nauwerck has described cells similar in character as being found in the urinary sediment in such cases, clinically.

Another important change is proliferation of these epithelial cells. This has been denied by some observers, who consider that the cellular increase is simply the result of desquamation. Herring considers that the change is chiefly observed in the cells lining the capsule. Fichera and Scaffidi have observed the change in the cells covering the tuft. In support of this proliferation, the last-mentioned authors advance their observation of the occurrence of layers of cells within the capsule, also of cells partially attached to the basal membrane and showing a normal appearance. This cell accumulation becomes vascularised, and ultimately contracts.

The question arises as to whether this cell multiplication takes place by means of direct or of indirect division. Fichera

and Scaffidi have never found true karyokinesis, although they occasionally observed appearances suggestive of it. They conclude that the process takes place by means of direct division. In support of this, they advance their observation of the occurrence of cells rich in protoplasm with two or more nuclei, and sometimes nuclei with a constriction in the centre apparently in the act of dividing. This proliferative process does not occur all over at the same time, nor does it occur in all the Malpighian corpuscles to the same extent.

The chief changes observed within the capillary tuft werediminution in the nucleated elements, increase in these elements, thrombosis, hyaline degeneration, and necrosis of capillary loops. As regards the first of these, sometimes the nuclear diminution was very evident, there being left behind simply an occasional leucocyte or endothelial cell. The vessel loops consisted of fine homogeneous structureless walls. This diminution occurred chiefly in those cases where there was a marked desquamation of the epithelium covering the tuft. This suggested the explanation that the two arose from the same cause, and that the absence of nuclei within the glomerulus was occasioned by the throwing off of the epithelial cells which occur between the lobes of the capillary tuft.

On the other hand, in cases of long-continued inflammation, one finds a marked increase in the nuclei. According to some, this is due to a multiplication of pre-existing cells of a connective tissue nature. The authors, however, reject this explanation, as they do not believe in the existence of such cells. They also reject the explanation that the phenomenon is due to a multiplication in the endothelial cells of the capillaries. According to them, it is to be explained by an excessive accumulation of leucocytes.

JAMES MILLER.

REVIEWS.

A Practical Guide to the Administration of the Nauheim

Treatment of Chronic Diseases of the Heart. By LESLIE
THORNE ABRAM, M.D. Durham. London : Baillière,

Tindall, and Cox. This is a short handbook for those who wish to prescribe the Nauheim treatment in England. Experience has shown that the method followed at Nauheim requires modification when employed by patients who are unable to travel abroad.

The author obtains his best results in cases of dilated irritable heart such as may follow influenza, the symptoms being palpitation, dyspnoea, insomnia, vertigo, cardiac pain, and lassitude. The first bath (containing four to five pounds of Droitwich salt, and five to six ounces of calcium chloride) is given for three to four minutes, at 97 to 98 degrees. The pulse is noted before and after. The patient goes to bed, and remains at perfect rest. These baths are continued on two consecutive days, while on the third day the “ Schott exercises are given instead of the bath. Later, a bath is taken three days running; the strength of the bath in suitable cases may be increased by one pound of salt and one ounce of calcium chloride. The length of immersion is increased by one minute daily. The temperature is lowered from 97 or 98 degrees to 94 or 93 degrees. Cases unsuitable for this method of treatment are those of alcoholic and syphilitic nature, or having other forms of myocardial degeneration. Several cases are given in support of the author's method.

Nouveau Formulaire Magistral. By A. AND G. BURCHARDAT.

Paris : Félix Alcan, 108, Boulevard Saint Germain. This is a publication which corresponds in some degree to the

Companion to the Pharmacopoeia." It gives the usual pharmaceutical formula and methods of preparation. French

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