Fig. 1

The abnormal intestinal architecture in brom bones.

(A) brom bones displays an enlarged abdomen (arrow) as compared to a wild-type sibling. (B) The dissected intestine of the wild-type fish shown in (A). The original coiled intestine tube was unfolded for a better view. Lines indicate the borders between anterior, mid and posterior intestines. (C) The intestine dissected from the brom bones mutant shown in (A). Note the abundant food waste in the intestine. Double arrows indicate the clear portion in the anterior intestine. Anterior is toward left. (D–K) Hematoxylin and Eosin (H&E) staining on cross-sections of the intestines from a wild-type fish (D and I), a brom bones heterozygous fish (E,J), and brom bones homozygous fish (F, G, H, and K). (D–H) From the anterior segments of the intestine. (I–K) From the mid segments. Arrows in (D) point to goblet cells. The severity of the intestinal phenotype varies among individual homozygous mutants. (F) represents brom bones homozygous intestines that display markedly reduced goblet cells. (G) represents brom bones homozygous intestines that exhibit excessive number of the intestinal epithelial cells and lack visible lamina propria. (H) is the cross-section of the brom bones intestine shown in (C), representing mutants with the big abdomen phenotype. Note that both the intestinal epithelium and the smooth muscle layer undergo degeneration. brb = brom bones; wt = wild-type; A = anterior intestine; M = mid intestine; P = posterior intestine. Scale bar = 50 μm.