Fig. 4

Reduction of podocytes inzepmutants occurs concomitantly with an expansion of the interrenal lineage. WT siblings and zep mutants have no difference in (A) cell proliferation based on pH3 staining and showed no differences in the amount of cell death (B) based on AO staining in the area where podocytes and interrenal cells arise. In contrast, (C) WT siblings have bilateral clusters of podocytes (P), identified by wt1b transcript localization (purple), and a centralized interrenal (IR) gland at the midline, identified by localization of nr5a1a transcripts (red) at 36 hpf. zep mutants show abrogated wt1b expression and a distinctly increased region of cells that express nr5a1a transcripts. (D) The region of cells exhibiting 3β-HSD staining is increased in zep mutants compared to WT siblings, with the area quantified (E). (F,G) There is significant increase of nearly two-fold in the volume occupied by the hormone secreting interrenal gland cells in zep mutants compared to WT, as visualized by FISH and confocal microscopy. Asterisks (*) indicate p < 0.001 using student T-test. Embryos are shown in dorsal views, where the white or black boxes demarcate the cervical region where podocytes and the interrenal gland develop. Insets show digital zoom view of 150%.