Scanning Electron Microscopy of the Podocytes of Renal Glomerulus

Abstract

The renal glomeruli of the rat and rabbit were observed under the scanning electron microscope with following results: 1. The podocyte lying inside of the curves of capillary convolution, radially extended several processes to the capillary walls which will be called primary processes. Thick primary processes ramified into secondary, and occasionally further into tertiary, processes, which, like fern leaves, issued slender foot-processes. Some of the primary processes of smaller size, without branching, directly sent out the foot-processes. 2. The secondary processes deriving either from the same or from different primary processes often were anastomosed with each other, forming a circuit of cytoplasm. Irregular thickenings of parts of processes were common. 3. It was clarified that the foot-processes of different cells were alternately juxtaposed on the capillary wall. An interdigitation of the processes from one and the same cell could never be found in the present materials. 4. In the rat the branching of the secondary and foot processes was generally at a right angle. The corresponding processes of the rabbit were characterized by an oblique branching and frequent dichotomy. 5. Microvilli of different lengths occurred on the cell body and processes of the podocytes. They were more numerous in the rat than in the rabbit. A few podocytes in the rat showed bud-like and ring-shaped microprocesses whose nature was unknown. 6. The inner surface of the glomerular capillary showed densely arranged endothelial pores. © 1970, International Society of Histology and Cytology. All rights reserved.