A morphologic study of the mesonephros of the human embryo

The fine structure of the mesonephros is studied in 7- and 10-week old human embryos. Marked morphologic differences are observed between the mesonephros and the definitive kidney. These differences relate to the morphology of the afferent and efferent glomerular vessels, endothelial cells of the glomerular capillaries, and epithelial cells of the proximal and distal tubules. The juxtaglomerular apparatus and the Henle loop are absent in the mesonephros. These dissimilarities are evaluated in light of the different functional performances of mesonephros and metanephros.