BMP7 promotes survival of the nephrogenic mesenchyme.
Mesenchyme was isolated from 11.5-dpc embryos and grown in culture for
48 hr in the presence of a bead containing BSA (A,B),
BMP7 (C,D), or FGF2 (E,F). Explants
treated with BSA appear granular and refractory to light. In contrast,
there is a well organized, translucent region of mesenchyme in the
vicinity of the BMP7-soaked bead (cf. cells indicated by arrow in
A and C). Staining with the vital dye TOPRO-1 reveals
that cells in the BSA-treated mesenchyme are dying as indicated by
fluorescent signal (B), whereas, in the BMP7-treated
mesenchyme, cells in the translucent region do not fluoresce,
indicating that these cells are viable (cf. cells indicated by arrow in
B and D). Interestingly, most of the cells in the
explant survive when treated with FGF2 (E,F). Note
that the heparin–Sepharose beads in E and F display
autofluorescence. (b) Bead. Scale bar, 100μm.