[Ultrastructural study of the distal convoluted tubule in the mouse embryo].

This work constitutes a contribution to the ultrastructural study of the differentiation of the epithelium of the distal convoluted tubule, which has been poorly investigated. The study was realised on mouse embryos B1 C57 (14th, 16th, 18th and 20th day of gestation), on newborn and one month old mice. On day-16 the distal convoluted tubule was evident in the form of a cellular mass; the lumen appeared on day-18. On day-20, completely differentiated epithelial cells were observed in some distal tubules; those cells showed cytoplasmic processes in the apical part, and basilar plasma membrane invaginations, containing mitochondria with numerous cristae. The results of this ultrastructural study confirmed that the differentiation of renal epithelium is progressive and indicates the installation of the renal function before birth.