Fig. 8

a–c Expression profile of Ci-Vsp by WISH. a Whole-mount (left) 2-week-old juvenile showing regional expressions in the stomach (st; arrow), bulged-region of the mid-intestine (int; arrowhead), and posterior-intestine (gray arrowhead). Higher magnification (right) reveals a stripe-like distribution of signals in the stomach and bulged intestine. b Dissected post-pharyngeal region of the digestive tract of the 1.5-month-old young adult showing an additional expression region (white arrowhead) in the looped-intestine. c Transverse section specimens of the juvenile (white line in a) showing Ci-Vsp expressions in the epithelium of the digestive tract (left). Expression signals in the stomach epithelium are restricted mainly in the inner-folds (white dotted lines), which contain several absorptive enterocytes³⁸, as opposed to the outer-folds (dotted lines) with many pancreatic-related exocrine gene expressions³⁹. Circumferences of the stomach (middle) and bulged intestine (right) show alternating epithelial morphology and Ci-Vsp expression. d–f Expression profile Ci-Dab2. d Whole-mount (left) 2-week-old juvenile showing regional expressions in the stomach (st; arrow), bulged-region of the mid-intestine (int; arrowhead), and posterior-intestine (gray arrowhead). Higher magnification (right) reveals a stripe-like distribution of signals in the stomach and bulged intestine. e Dissected post-pharyngeal region of the digestive tract of the 1.5-month-old young adult showing an additional expression region (white arrowhead) in the looped-intestine. f Transverse section specimens of the juvenile (white line in d) showing Ci-Dab2 expressions in the epithelium of the digestive tract (left). Expression signals in the stomach epithelium are restricted mainly in the inner-folds (white dotted lines) as opposed to the outer-folds (dotted lines). Circumferences of the stomach (middle) and bulged intestine (right) show alternating epithelial morphology and Ci-Dab2 expression. Scale bars = 200 µm in a, d, 1 mm in b, e, and 50 µm in c, f. OS oral siphon, AS atrial siphon, Ph pharynx, En endostyle, Stg stigma, Es esophagus, Nc neural complex, Gd gonad.