Glomerular podocytes in developing quail kidney

Abstract

In metanephric kidneys of Japanese quail, the number of glomeruli increases exponentially during the later embryonic stage and early postnatal days. In the surface area of developing metanephric kidneys, condensed areas that contain undifferentiated cells are seen. In this mesenchymal region, no mature tubules are present. In contrast, in the inward area, mature glomeruli, proximal tubules consisting of columnar epithelial cells, and cuboidal distal tubules are seen. The condensate zone decreases in size with maturation, but is still detectable at 3‐postnatal week. We examined podocytes (glomerular epithelial cells) and slit diaphragms in developing quail kidneys. Podocyte foot processes with irregular size and intervals are recognized at embryonic day 15 and postnatal day 5 (D5) of metanephros. Foot processes are fused in some location. Slit membranes connecting adjacent foot processes are more clearly seen after D14. Podocin and nephrin, which are important in maintaining integrity and permeability of the slit membrane, were recognized histochemically (immunoreactive against anti‐rat or anti‐mouse antibody) at D4 and D14, respectively, and thereafter. These results suggest that in quail kidneys that 1) nephrogenesis continues after birth and 2) molecular constituents of glomeruli also develop with structural maturation (NSF IOB0615359, NIH HL52881, JSPS17390247).