(A) Visceral anatomy of sea cucumber. The intestine is subdivided into the anterior descending small intestine, ascending small intestine, and the posterior descending large intestine. Abbreviations: short esophagus (E); anterior descending intestine (ADI); medial ascending intestine (MAI); posterior descending intestine (PDI). (B) Tissue organization of the luminal epithelium and (C) mesothelium found throughout the intestine of H. glaberrima. Abbreviations: basal lamina (bl); bundles of intermediate filaments in peritoneocytes (if); myoepithelial cell (m); mucocyte (mc); neuron (n); neurosecretory cell (ns); nervous plexus (np); peritoneal cell (pc); secretory vacuoles (sv); vesicular enterocyte (ve). Fig. 2 A adapted from García-Arrarás et al., 2019, Seminars in Cell & Developmental Biology 92, p. 47 and fig 2 B, C from Mashanov & García-Arrarás, 2011, Biological Bulletin, 221, p. 95. Copyright 2019 by Elsevier (2 A) and 2011 by The University of Chicago Press (2 B, C). Adapted with permission.