In vitro segregation of the metanephric nephron

In vitro segregation of the metanephric nephron was examined using three probes for the main segments: fluorochrome-conjugated wheat germ agglutinin (WGA) binding to the glomerular epithelial surface, an antiserum against the brush-border antigens (BB) of the proximal tubules, and an antiserum against the Tamm-Horsfall glycoprotein (TH) of the distal tubules. In vivo, these markers appeared sequentially on Days 13 to 15. The same sequence was obtained in experimental recombinants of the metanephric mesenchyme and its inductor. When the inductor was removed after a 24 hr initial transfilter contact with the mesenchyme, segregation was similarly observed after subculture of the isolated mesenchyme. Hence, the sequential, multiphase differentiation of the nephron is initiated during a short induction period.