Fig. 1. The numbers of NCSCs, neurons and glia are reduced in the gut after Rbpsuh deletion. (A,B) Transverse sections of the guts from E13.5 control (A) or Wnt1-Cre⁺ Rbpsuh^fl/fl (B) mouse embryos were stained for neurons (TuJ1) and glia (BFABP). Scalebar: 10 µm. (C) The numbers of p75⁺ neural crest cells that initially colonized the gut did not differ between E10.5 control and Wnt1-Cre⁺ Rbpsuh^fl/fl embryos (the number of p75⁺ cells per section; three sections per gut region per mouse, three mice per genotype). (D-F) At representative levels of the developing gut (foregut, midgut and hindgut), the numbers of neurons (TuJ1⁺) and glia (BFABP⁺) per section were similar to wild type in Wnt1-Cre⁺ Rbpsuh^fl/fl embryos at E10.5 (D) but significantly (^*, P<0.05) lower at E14.5 (E) and E18.5 (F). (G) There was no difference in the rate of proliferation of p75⁺ cells at E14.5 between control and mutant embryos (BrdU was administered for 30 minutes; three to seven sections per gut region per mouse, three to four mice per genotype). Additionally there was no significant difference in the rate of cell death between control and mutant mice at any stage of development (E10.5, E14.5 and E18.5) or at any level of the gut (foregut, midgut and hindgut) based on staining for activated caspase 3 (data not shown). (H) However, a significantly (^*, P<0.05) lower percentage of cells from E13.5 Wnt1-Cre⁺ Rbpsuh^fl/fl guts gave rise to multilineage NCSC colonies in clonal-density cultures in both standard medium and medium supplemented with neuregulin (+Nrg) (three to seven independent experiments). All error bars indicate s.d.