Immunohistochemical localization of NPY, VIP and 5-HT in the thyroid gland of the lizard, Podarcis sicula

Abstract

The thyroid gland of the lizard Podarcis sicula was immunohistochemically studied in adult male specimens using specific antibodies against NPY, VIP and 5-HT and the avidin-biotin peroxidase complex (ABC) procedure to localize the three peptides. Fine beaded VIP-immunoreactive nerve fibers ran between the follicles, and VIP-immunoreactivity was evenly distributed in the apical cytoplasm of follicular cells. NPY-immunoreactive fibers were found around the follicles, and, in the cells, immunoreactivity was localizated only in the cellular apices. Immunoreactivity to 5-HT was observed in the colloid, with a concentration in the follicular lumen exceeding that in the follicular cells. In fact, most follicles showed immunoreactivity in the cytoplasmic bridges formed between the apical portion of the follicular cells and the colloid.