Ultrastructural differentiation of the glomerular mesangium from the human metanephros.

In section of metanephros tissue obtained from 32 human embryos and fetuses, 8 to 24 weeks old, the mesangial cells differentiate beginning with the 12th week. Some of the cells from the central mass of the metanephros blastema showed endocytosis phenomena characteristic for the adult mesangial cells. In the 13th week the three cellular types from the renal corpuscle individualize, and from the 14th to the 16th week they acquired the adult morphological aspect.