Fig. 1 ascl1a is expressed in the precursor cells of the gastrointestinal tract. Ventral views with anterior on the left of embryos analyzed by visible WISH (A–D) or double fluorescent WISH (E and F). (A) General view of ascl1a expression domain at 55 hpf. (B) At 40 hpf, ascl1a is expressed in cuboïdal cells scattered in the primitive intestine (dotted lines) and in enteric neurones that lined these cells (arrows). (C) At 58 hpf, this scattered expression is still intense. (D) At 72 hpf, the number of ascl1a expressing cells begins to decrease along the gastrointestinal tract. (E and F) Confocal sections showing that ascl1a is not expressed in the mature enteroendocrine cells labeled by the gcga probe (E) neither in the mature goblet cells labeled by agr2 (F). Scale bars: 50 μM.
Reprinted from Developmental Biology, 376(2), Flasse, L., Stern, D.G., Pirson, J.L., Manfroid, I., Peers, B., and Voz, M.L., The bHLH transcription factor Ascl1a is essential for the specification of the intestinal secretory cells and mediates Notch signaling in the zebrafish intestine, 187-197, Copyright (2013) with permission from Elsevier. Full text @ Dev. Biol.