stag es of development of renal glomeruli in the newborn rat kidney

glomerular development of the kidney was studied in newborn rats by electron microscopy. four different stages of glomerular development were defined: vesicle fonnation, s-shaped body stage, capillary loop fonnation, and glomerular maturation. in the fust stage, the mesenchymal cells form a spheroid mass. this is followed by the s-shaped body stage in which clefts appear in the mass. afterwards, capillary loop formation, junctional migration, podocyte differentiation, and interdigitation of epithelial processes occur. finally, the cytoplasm of endothelial cells becomes thinner. the urinary space is visible in this stage. the fusion of epithelial and endothelial basement membranes results in fonnation of the layers of the gbm. the increase in the number of podocyte processes and endothelial cell fenestrations are important events in the maturation phase.