[An analysis of the ultrastructure of epithelial cells of the rat proximal tubule at early stages of penicillin elimination].

A study was made of the ultrastructure of epithelial cells of the rat proximal tubules nephrons 25-30 seconds, and 15 and 30 minutes following penicillin injection. The morphological changes in the transporting cells that were observed involved the dilation of the inner cavities of canals and cisterns of the endoplasmic reticulum. The number of elements of the smooth endoplasmic reticulum concentrated on the periphery of the cell, near the basolateral border, was seen to increase. Microbodies appeared enlarged with the appearance of the nucleolus; the electron density of the cytoplasmic ground substance fell down. The space between cells augmented, and the interstitial space between infoldings of the basal plasmalemma was much broadened. Similar morphological changes but different in the intensity were found at either stage examined. The maximum changes were established 25-30 seconds following penicillin injection.