Distribution, histochemistry and ultrastructure of somatostatin-like immunoreactive cells in the gastroenteric tract of the cartilaginous fishScyliorhinus stellaris (L.)

Abstract

Somatostatin-like immunoreactive cells of an open type have been identified in the digestive tract of the cartilaginous fish Scyliorhinus stellaris (L.) by the use of immunocytochemical techniques. In the stomach these cells are numerous both in the corpus (neck zone and tubular glands) and in the pyloric portion (crypts). In the spiral valve, somatostatin-like cells are rare, situated in the intestinal epithelium and without any particular localization. Using semithin serial sections, somatostatin-like cells are found to be Davenport-negative and weakly positive towards the Grimelius silver reaction, and using the semithin and ultrathin technique have been identified at the ultrastructural level; their secretory granules appear electron dense, round or slightly polygonal, and with a limiting membrane tightly adherent to the core. The mean diameter varies from 250-300 nm.

Histology of the digestive tract of the freshwater stingray Himantura signifer Compagno and Roberts, 1982 (Elasmobranchii, Dasyatidae)

“…In our study, by using a Grimelius silver reaction, we detected a part of the EC population, namely those cells rich in serotonin (Hould 1994). The highest number of EC present in the stomach of H. signifer is in accordance to previous studies in nurse-hound shark, Scyliorhinus stellaris (Tagliafierro et al 1985) and R. asterias (Tagliafierro et al 1989). Most of the EC were of the open type, meaning that hormones are transported to the gut lumen by long cytoplasm processes (Pan et al 2000).…”

“…Enteroendocrine cells have been extensively studied in mammals and in teleosts (Pan et al 2000;Buddington and Krogdahl 2004), but the information on these cells in cartilaginous fishes is still scarce (Hakanson et al 1986;Tagliafierro et al 1985Tagliafierro et al , 1988Tagliafierro et al , 1989Falkmer 1993). In our study, by using a Grimelius silver reaction, we detected a part of the EC population, namely those cells rich in serotonin (Hould 1994).…”

“…Indeed, indiscriminate direct use of human medical nomenclature is often not advisable, because it can be misleading. For instance, in the stomach the most used terms for the two main regions, cardiac and pyloric (Holmgren and Nilsson 1999) or corpus and pyloric (Tagliafierro et al 1985), can be misleading by implying that both these regions are glandular or somehow similar to a mammalian model; for these regions, the terms we used (descending and ascending) seem preferable. The same is true for the intestine, in which the anterior and posterior intestines have been called small intestine (or duodenum or ileum) and large intestine (or rectum), respectively (Yokote 1982).…”

Comparative Neuroendocrinology of Gut Peptides

“…In mammals somatostatin-containing endocrine cells are common in the gut mucosa, especially in the stomach, and there are somatostatin-containing neurons that, at least in the ileum, may also contain CCK. Endocrine cells have been found in the gut of most major chordate groups, including birds, reptiles, amphibians, teleosts, elasmobranchs, and protochordates (42,107,109,133,167,168,170,209,227,272,319,341,386). The distribution of the somatostatin variants of the lower vertebrates is not well understood.…”