Ultrastructural characteristics of human foetal kidney. I: S.E.M. observations

With the aim to studying the main steps which characterize the early development of the human foetal kidney, fragments of renal bud of 8-12 weeks of pregnancy have been processed for scanning electron microscopy. The results can be summarized as follows: first generation of nephrons appear after the 8th week of development; during this period kidney bud change from a condition of very simple organization to an higher differentiated structure, especially in cortical part of the bud, at level of juxtamedullar nephrons. It is possible to observe the differentiation of primary podocytes that arrive, with their deeper cytoplasmic projections at level of the capillaries wall, giving rise to the typical structures of filtration barrier. The tubular structures maintain the differentiation observed in the earlier phase of the development. The obtained results demonstrate that the developing kidney buds undergo deep changes, at level of the parenchime and vascular system, during the studied period.