Fig. 1

Intestinal expression of ascl1a. ascl1a is expressed in a few intestinal epithelial cells at 44 hpf throughout the length of the intestine ((A), arrow points to intestine). Higher magnification (B) shows individual epithelial cells expressing ascl1a, which is sparse and light at this stage. The number of cells expressing ascl1a increases by 48 hpf ((C), arrow points to intestine) and higher magnification (D). This changes at 50 hpf (E), when ascl1a is expressed more evenly throughout the intestinal epithelium, often in clusters of cells (higher magnification in (F)). In cross section at 50 hpf a single section will often display multiple epithelial cells expressing ascl1a (arrows in (I)). Expression of ascl1a is still strong in the intestinal epithelium at 74 hpf ((G), arrow points to intestine) but cells are often less clustered. Cross sections more frequently display single epithelial cells expressing ascl1a (arrow in (J)). All whole mount images ((A)–(H)) are oriented anterior to left and posterior to right. Scale bars: (A), (C), (E), and (G) 200 μm; (B), (D), (F), and (H) 50 μm; (I) and (J) 20 μm.