The aim of this study was to describe the bovine renal system development, during the early embryonic period (10-50 days). Bovine embryos collected in abattoir were photographed and measured by Crow-Rump (CR) method to estimate the gestational age. The embryos destined to optical microscopy were fixed in Bouin solution for development evaluations of renal system, as well as its structures. Some embryos also were fixed in Glutaraldeheyde 2.5% and destined to transmission electron microscopy for ultrastructural study of renal system cells. In bovine embryos with gestational age of 14 to 15 days (E14-15) the presence of pronephro were not observed, however the mesonephro was found, as well as morphologic indications of it is functional activity. Mesonephro presented, in the interior of its tubular cells, innumerable mitochondrias and interdigitations, indicating high activity of ionic transportation. The metanephro, or definitive kidney, initiates its development in E23-24. The study demonstrated that the involution of mesonephro happened simultaneously with the metanephrogenic differentiation. In E45-46, the embryos already initiated the fetal phase, and the metanephro possess the filter units (nephrons), with its respective glomeruli, proximal and distal convoluted tubules, and the loop of Henle.
bovine kidney; embryonic development; morphology; renal system
