Fig. 1. EDTA treatment allows the visualization of whole rabbit dome epithelium and its associated crypts. Rabbit epithelium from appendix (A-C) and caecal patch (D,E) were isolated from the underlying tissue by EDTA before fixation according to the Materials and Methods. (A) Side view of an apex-less dome (broken line) seen through its associated surrounding colonic epithelium by trans-illumination; intact crypts are distributed regularly around the dome base (arrowheads). (B) Dome epithelium revealed by pulling down the surrounding colonic epithelium. Arrowheads mark each end of the crevice from which crypts supply, first, M cells and enterocytes to the dome above (broken line), and, second, goblet cells and enterocytes to the colonic epithelium (lower part of the figure, bracket). The colonic epithelium, normally lying in apposition to the dome, is clearly visible under the crypt row (arrowheads) down to the beginning of its apical surface, characterized by long tubular structures opening on the apex (arrows). (C) Tearing away the colonic epithelium left only the FAE with its associated crypts (arrowheads and inset). Note the central apex torn off during isolation treatment. (D) Bottom view (in bright field) of dissociated caecal patch crypts lined up in several rows. (E) DIC side view of caecal patch crypts, with some of them branched.
