[Development of the renal glomerulus examined by transmission and scanning electron microscopy]

The kidneys of 2 to 10 days old albino rats were fixed by perfusion and examined by transmission and scanning electron microscopy. Furthermore, vascular casts of renal vessels in rats of the same ages were effectuated by injection of methacrylate into the aorta and observed by SEM. The observation of glomerulogenesis in different stages has indicated that the glomerular capillaries originate in the interstitial vessels which penetrate into the cleft formed in the wall of the renal vesicle. Initially the capillaries have an aspect of small sinusoids which then expand peripherally and undergo successive subdivisions: the anastomosis in each glomerular lobule persists. The podocytes originate from the cells of the renal vesicle facing the penetrating capillaries. The initially primitive cells branch off successively and extend around the expanding capillaries with their small processes -- the foot processes which interdigitate with the corresponding structures of the neighbour cells.