ABSTRACT
The esophagus of Holothuria scabra begins where the peripharyngeal mesentery joins the gut. At this point, the circular and longitudinal muscle fibers in the gut cross over. Posteriorly, the transition between the esophagus and the stomach occurs at the end of the first constriction of the gut. The autotomy region of the esophagus lies within this constriction. The autotomy region is distinguished by a cell mass of early stage lymphocyte-like cells in the connective tissue layer. The visceral mesentery consists of a portion proximal to the gut, and a portion distal to the gut. The mesentery is also bilaterally differentiated. The autotomy region of the mesentery occurs within the distal mesentery. Structural adaptations which minimise damage or facilitate regeneration appear to be lacking in the autotomy regions of the esophagus and mesentery.
