Localization of calbindin-D28K in calcitonin containing cells of chick ultimobranchial glands

Expression of calbindin-D28k in developing and growing chick testes

Calbindin, a 28-kDa vitamin D-dependent calcium-binding protein was localized immunohistochemically in developing and growing chick testes. The protein first appeared in the germinal epithelium of developing testes of the eight-day-old embryo and remained therein throughout development. Calbindin was not present in the germinal epithelium after hatching. Calbindin was next detected in the spermatogonia and spermatocytes of one-week-old and growing chick testes. Calbindin-positive spermatogonia and spermatocytes gradually increased in number and staining intensity as the seminiferous tubules further developed. A few interstitial Leydig cells were positive for calbindin from five-week-old and older chicks. Comparison of the time-course of appearance and increase in calbindin content in spermatogonia and spermatocytes with spermatogenesis in chickens suggests that calbindin may be involved in the mitotic process in spermatogonia and spermatocytes.

Immunocytochemical localization of vitamin D-dependent calcium-binding protein (calbindin) in thyroid parafollicular cells of guinea pig

The presence of the 28K vitamin D-dependent, calcium-binding protein (28K calbindin) was investigated by immunocytochemistry in normal thyroid glands and parathyroid glands of rats, guinea pigs, rabbits and men, as well as in human thyroid medullary carcinomas and human parathyroid adenomas. In addition, thyroid glands and parathyroid glands of rats and guinea pigs were studied after treatment with vitamin D3 injected intramuscularly at a total dose of 1.2 x 10(6) IU per 100 g body weight. 28K calbindin was found exclusively in parafollicular cells of guinea pigs and never in those of other species investigated. It was present predominantly in the cytoplasm and in lower concentration in nuclei. After vitamin D3 treatment, increased immunoreactivity of 28K calbindin was observed in the cytoplasm and, even more pronounced, in the nuclei. In normal parathyroid cells and in parathyroid tumors and medullary thyroid carcinomas, 28K calbindin was not demonstrable. Our findings suggest an important function of calbindin in the cellular calcium processing of parafollicular cells of guinea pigs.

Calbindin 28 kDa in endocrine cells of known or putative calcium-regulating function. Thyro-parathyroid C cells, gastric ECL cells, intestinal secretin and enteroglucagon cells, pancreatic glucagon, insulin and PP cells, adrenal medullary NA cells and some pituitary (TSH?) cells

The distribution of calbindin in some endocrine glands (thyroid, parathyroid, ultimobranchial body, pituitary and adrenals) and in the diffuse endocrine cells of the gut and pancreas has been investigated immunohistochemically using an antiserum raised against the 28 kDa calbindin from chicken duodenum. The identity of calbindin-immunoreactive cells in a number of avian and mammalian species was ascertained by comparison with hormone-reactive cells in consecutive sections or by double immunostaining of the same section with both calbindin and hormone antibodies. Calcitonin-producing C cells of the mammalian and avian thyroid, parathyroid or ultimobranchial body, PP, glucagon and insulin cells of the mammalian and avian pancreas, enteroglucagon cells of the avian intestine, secretin cells of the mammalian duodenum, histamine-producing ECL cells of the mammalian stomach, as well as noradrenaline-producing cells of the adrenal medulla and some (TSH?) cells of the adenohypophysis were among the calbindin-immunoreactive cells. Although some species variability has been observed in the intensity and distribution of the immunoreactivity, especially in the pancreas and the gut, a role for calbindin in the mechanisms of calcium-mediated endocrine cell stimulation or of intracellular and extracellular calcium homeostasis is suggested.