Studies on the pancreatic D cells in the chicken.

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Somatostatin (SS) is a peptide containing 14 amino acid and isolated from the ovine hypothalamus. SS was found not only in nervous tissue but also endocrine cells. SS-28 consisting of an N-terminal extension of SS-14 is widely distributed in vertebrates. SS-14 and SS-28 may occur from the same precursor, and SS-14 is experimentally produced from the cleavage of SS-28. It may be a terminal product. The close association of SS-28 with glucagon cells, and of SS-14 with insulin cells, in the fish islets is implied. SS-28 is more potent than SS-14 in the inhibition of insulin release, but SS-14 preferentially inhibits glucagon release. The main object is immunohistochemically to elucidate whether the different forms of SS are produced in D-cells of A and B islets. Materials and Methods. Pancreas and adrenals of several species of birds and mammals were fixed with paraformaldehyde and mounted with paraplast. Serial sections 4mum in thickness were cut and performed the immunohistochemical staining by ABC method. Of six kinds of SS-antisera used, specificity of the antisera for SS-14 and SS-28 [1-28] was tested by preabsorption with SS-14 and SS-28[1-14]antigens.Results and Discussion. D-cells of islets and intestine, and A cells of adrenals in chickens stained with antisera against SS-14 and SS-28 [15-28] , but not with SS-28 [1-14]. Islet D-cells of crows, geese and ostrich also are immunoreactive for SS-14, but not for SS-28 [1-14]. Contrarity, islet D-cells of cats, serows and musk shrews immunostained for SS-14 and SS-28[1-14]. Adrenal A cells of goats and cats reacted with the antisera against SS-14 and SS-28 [1-14].Taken together, both islet D cells and adrenal A cells contain only SS-14 in the avian species. It seems likely that avian species is characteristic of somatostatin in the evolution.