The possible sites of renin formation in the kidneys of the experimental hypertensive rabbits.

Two theories concerning the site of renin formation have been known. One is proposed by Goormaghtigh(1940, 47)who assumed juxtaglomerular cells to be responsible for the production of renin on the basis that the cells hypertrophy and the granulation in them augments in degree in the experimental hypertensive animals. The other is proximal convolution theory adovocated by Friedman and Kaplan(1942a, 42b, 42c, 43)from the experimental proof that renin disappears from the kidney of the subcutaneously administered rabbits with Na-tartrate, when proximal convolution epithelial cells undergo severe damage or necrosis. Supported by Selye(1952), this theory has been accepted by a number of investigators. Recently, Yoshimura and Negishi(1954)substantiated that the vasopressor effect of renin extracted from the kidney of the rabbits injected with Na-tartrate would be neither enervated nor accelerated. Nevertheless, Yoshimura and Tsunoda(1955)confirmed the definite degenerative figures in proximal convolution epithelial cells of the same animals, casting a doubt to Friedman and Kaplans' view. Also they were successful in making the pronounced hyper granulation in juxtaglomerular cells by the chemical administration. This would enable the ground of the theory that juxtaglomerular cells produce renin to be anything but convincing. Previously, Yoshimura and Nemoto(1953)found the particular dark-shaded cells charged with abundant mitochondria("dark cell"of Yoshimura and Nemoto) within epithelium of the distal segments of the mammalian renal tubules. Especially in the amphibian kidney, according to Yoshimura and Sunaga(1952)the cells are characterized by the sign of endocrine activity which may be regulated under the anterior lobe of pituitary. In mammals, however, these cells lack in the endocrine figures. In present investigation the authors will examine the cytological alterations in three possible sites of renin formation in the experimental renal hypertensive rabbits with the moderate constriction of main renal artery.