Fig. 12

Histological details of the mid- and hindgut of Stephanella hina. a Longitudinal section of a polypide showing the transition of the esophagus to the cardia and parts of the caecum. b Close-up of the cardiac valve and cells of the cardia. c–e Detailed images of the cellular architecture of the caecum epithelium showing its variable cellular architecture. f Details of the cells of the intestine. g Detail of the anal area entering the tentacle sheath. Abbreviations: a - anus, ban - basal nuclei, ca - cardia, cae - caecum, cv - cardiac valve, es - esophagus, gh - ganglion horn, gtl - gut lumen, lb. - lophophoral base, ph - pharynx, rm. - retractor muscles, ts – tentacle sheath