Immunohistochemical studies of renin-containing cells in the developing sheep kidney

Renin-containing (RC) cells in small ruminant kidneys have been known to be widely distributed along the blood vessels. In the present study, RC cells in developing sheep kidneys were studied to investigate not only the appearance but distribution with the potential physiological significance using immunohistochemical and histoplanimetrical techniques.

Seven fetal, 12 newborn, and 3 adult metanephric kidneys were used and immunostained by anti-renin antiserum. In the histoplanimetrical analysis, the numerical values of RC cells existing at the walls of 3 major arterial types in the kidneys were calculated.

At day 44 of gestation, RC cells were already demonstrated in the walls of renal, interlobar, and afferent vessels, located in the deep cortex and the medulla. In intermediate gestational periods, RC cells were detected throughout the intrarenal arterial trees. In late gestational periods, RC cells expressed in the walls of interlobar/arcuate and interlobular arteries tended to decrease or disappear gradually, while they were distributed predominantly in the afferent glomerular vessels. In newborn lambs, especially days 1 to 3 after birth, increased numbers of RC cells were demonstrated throughout the arterial trees in the kidneys. In older lambs, RC cells located in the interlobar/arcuate arteries and the proximal region of the interlobular arteries decreased in number and gradually disappeared. Some RC cells were still distributed in the distal portion of the interlobular artery even in the adult sheep.

These results suggest that the wide distribution of RC cells in sheep kidney is formed in perinatal life, and that the neuronal regulation is associated with the maintenance of this distribution.