ACCESSORY CAROTID-BODY WITHIN THE PARATHYROID-GLAND-III OF THE CHICKEN

In the chicken, the cranial and caudal parathyroid glands (parathyroid gland III and IV), which are connected to each other, are located adj acent to the carotid body. In the present study, we found that a mass of glomus cells surrounded by a thick layer of connective tissue was f requently distributed within the parathyroid gland III. The glomus cel ls in the parathyroid III, as well as those of the carotid body, expre ssed intense immunoreactivity for serotonin, chromogranin A, and tyros ine hydroxylase but no immunoreactivity for neuropeptide Y. The cells possessed long cytoplasmic processes containing dense-cored vesicles o f 70-220 nm in diameter, and were in close association with sustentacu lar cells. In and around the glomus cell clusters of the parathyroid I II, dense networks of varicose fibers showed immuno-staining with the monoclonal antibody TuJ1 to a neuron-specific class III beta-tubulin i sotype, c beta 4. Furthermore, the distribution was also detected of n umerous galanin-, vasoactive intestinal peptide (VIP)-, substance P-, and calcitonin gene-related peptide (CGRP)-immunoreactive fibers.