The centrolobular region of the renal glomerulus studied by electron microscopy

Abstract

Centrolobular regions of rat kidney glomeruli were studied electron microscopically after fixation in the living animal and embedding in Araldite or Epon. Intercapillary cells within these regions are separated from adjacent capillary lumens by endothelial cells. The endothelial cell may be represented by a portion containing the nucleus, but more often by a thin layer of cytoplasm having occasional gaps or holes. In contrast to endothelial cells, intercapillary cells have many branching processes which have not been found to extend to the capillary lumen. An amorphous intercellular substance fills much but not all of the centrolobular space between intercapillary cells and their processes. The central dense layer of the basement membrane follows the epithelium over the centrolobular region without splitting and entering it or sending a layer beneath the central portions of endothelial cells. After intravenous injection of thorotrast, particles enter the centrolobular region in high concentrations within 5 to 10 minutes, penetrating intercapillary channels through the intercellular substance between intercapillary cells. These observations suggest that centrolobular regions and intercapillary cells may play special roles in the control of capillary flow and in reactions to pathologic agents.