STUDIES ON VISCERAL REGENERATION IN SEA-STARS. III. REGENERATION OF THE CARDIAC STOMACH IN ASTERIAS FORBESI (DESOR)

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Abstract
Not later than 48 hours after removal of the cardiac stomach in A. forbesi, the integrity of the gut wall and the coelom is restored by fusion of the cut edges and formation of a thick scar area, over which the epithelia of the pyloric stomach and the peristome join to produce a continuous lining. Reorganization and phagocytic debris-removal constitute the only apparent changes through the 1st 3 postoperative days; by 96 hours, mitotic activity begins, along with increase in size of the regenerating stomach. Growth and differentiation continue rapidly, and as early as the 15th day normal feeding and digestion are possible, with eversion of the regenerated stomach to surround and ingest food. The formation of the normal pattern of intrinsic retractor fibers, and of the gutter-patterns in the stomach wall with which they are associated, requires that the related extrinsic retractor nodule re-established proper contact with the scar area at the time of healing. Failure of contact results in marked inhibition of development in the sectors of the stomach involved; no gutter-patterns form, no intrinsic fibers branch over the surface, and the normal interdigitation of distinctive epithelial types characteristic of the gutters and the intervening ridges fails to develop. Study of these developmental anomalies emphasizes the fact that the normal patterns of fibers, gutters, and cell-types are closely interdependent, but evidence to date is insufficient to establish a precise causal sequence of events in their production. It is concluded that the tall cells with multiple flagella and dense, elongate nuclei, localized on the ridges between gutter, are distinct from the spindle-shaped sensory receptors in the stomach lining and in fact represent the basic epithelial cell type in the esophagus and adjacent oral regions of the stomach. Their origin in the regenerating stomach, where they reappear during the 2nd week of regeneration after complete extirpation, as well as the functional significance of their nuclear peculiarities, remain obscure.