Development and organization of the zebrafish intestinal epithelial stem cell niche.

BACKGROUND: Development of the vertebrate intestinal epithelial stem cell niche begins during embryogenesis but maturation occurs post-embryonic. The intestinal mammalian crypt contains stem cells interspersed by secretory cells that play a role in regulation of proliferation. Epithelial cells are specified as either secretory or enterocytes as they migrate up the villi in mammals or fold in zebrafish. Zebrafish forms a functional intestine by the end of embryogenesis but takes another four weeks to develop the adult proliferation pattern.

RESULTS: We characterize development of the intestinal epithelial stem cell niche during the post-embryonic period. During the first two-weeks post embryogenesis, different groups of epithelial cells sequentially proceed through one or two cell cycles, appear to become quiescent, and remain at the interfold base. The third week begins asymmetric divisions with proliferative progeny moving up the folds. Apoptotic cells are not observed at the fold tip until the end of the fourth week. Secretory cells intersperse among interfold base proliferative cells, increasing in number during the third and fourth weeks with a coincident change in proliferation pattern.

CONCLUSIONS: Zebrafish post-embryonic intestinal epithelial development consists of two weeks of slow proliferation followed by two weeks of metamorphosis to the adult structure. This article is protected by copyright. All rights reserved.