S-100 immunoreactive cells in non-nervous duck tissues.

S-100 protein was detected in endocrine cells of the islet of Langerhans, hypophysis, ultimobranchial body, proventriculus, gizzard and intestine, and epithelial cells of the interlobular bile duct, gall bladder, renal tubules and epididymal and urinary ducts except for the nerve elements in the duck. Sertoli cells and oocytes were also S-100-protein immuno-reactive. The types of S-100-protein-positive cells detected in the duck differ from those of mammalian species.