In nephrotic syndromes podocytes synthesize and excrete proteins into the tubular fluid: an electron and ion microscopic study

Abstract

Described here are the findings of an electron and ion microscopic study of renal biopsies of young children, with a particular attention to the intracytoplasmic and intranuclear changes observed in the podocytes of the proteinuric patients. In the cytoplasm, there is a considerable development of the ergastoplasm, associated with a dilatation of the endoplasmic reticulum and with the formation of large vacuoles containing nitrogen and sulfur. These changes are characteristics of cells synthesizing and excreting proteins. In the nuclei of many podocytes, the most striking change is a complete or quasi-complete disappearance of condensed chromatin, suggesting an intense transcription activity of the corresponding cells. The amount of the proteins excreted from the podocytes must be considered as significant, even if a quantitative evaluation was not possible.