Immunohistochemical study of cyst structures in chick ultimobranchial glands.

In order to clarify the functional significance of cyst structures located in ultimobranchial glands, chick ultimobranchial glands of various ages were investigated by an immunoperoxidase method using anti-calcitonin, anti-somatostatin and anti-19S-thyroglobulin antisera. At hatching, the cysts were consistent features of the chick ultimobranchial glands. With aging, they gradually increased in volume and number. In adult chickens, a major portion of ultimobranchial glands was occupied by cysts of various sizes, shapes and luminal contents. Some cyst epithelium consisted of calcitonin-positive cells alone, and a portion of the cystic contents was intensely immunoreactive to the calcitonin antiserum. Neither cyst epithelium nor luminal contents were stained with the 19S-thyroglobulin or the somatostatin antiserum. The present study indicates that some cyst structures of chick ultimobranchial glands are related to the synthesis, secretion and accumulation of calcitonin.