Fig. 3

Fig. 3 Ascl1a is a key regulator of the secretory cell differentiation cascade. (A) Diagram illustrating the expression window of the transcription factors and hormones in the gastrointestinal tract. The interval of time where the gene has been shown to be expressed is represented by a solid line whereas the gene expression was not analyzed during the periods outlined by dotted lines. The references for these data are as follows: a (this paper), b (Ng et al., 2005), c (Zecchin et al., 2007), d (Delporte et al., 2008), e (Wallace et al., 2005). (B–L) Ventral views with anterior to the left of embryos analyzed by fluorescent WISH (B–J) or visible WISH (K and L) (B–D) Confocal sections showing that ascl1a expression co-localize perfectly with sox4b expression in scattered cells of the primitive intestine (dotted line) at 48 hpf. (E–J) Confocal projections showing that all the gastrointestinal cells expressing sox4b, isl1 or rfx6 are absent in the pia mutant whereas the pancreatic expression of these factors is not affected (K and L) ascl1a expression is not affected upon Sox4b knock-down. P, pancreas; Arrow, enteric neurone. Scale bars: 50 μM.