IMMUNOLOCALIZATION OF REGULATORY PEPTIDES AND 5-HT IN BOVINE MALE UROGENITAL APPARATUS

Specimens of testis, excurrent duct including the accessory genital gl ands and urethra throughout its extension were investigated in adult b ovines, in order to immunohistochemically localize both the peptidergi c innervation and the epithelial cell types belonging to the diffuse e ndocrine system (DES). Immunoreactivities to GRP, met- and leu-enkepha lins, CGRP, NPY, substance P, VIP, somatostatin, beta-endorphin and 5- HT antisera were tested by means of a labelled streptavidin-biotin (LS AB) method. Such regulatory substances were found in components of the peripheral nervous system (nerve fibers in the connective and muscula r tissues, sub- and intraepithelial nerve terminals, nerve cell bodies and fibers in intramural ganglia), and in epithelial endocrine/paracr ine cells. Bovine urogenital apparatus is supplied by many peptide-con taining nerves, which contain in many localizations GRP and enkephalin s, and to a lesser extent substance P, CGRP, NPY and VIP. A thin netwo rk of peptidergic nerves distributes to the musculature of the canalic ular organs and accessory glands. The prostatic complex was especially rich in peptidergic innervation, and also contained somatostatin- and 5-HT-secreting endocrine cells. In addition, 5-HT-immunoreactive endo crine cells were found in the bulbourethral gland and urethral epithel ium. CGRP-ir nerves were present contacting striated muscle fibers of urethra (motor end plates). The testis was devoid of any immunoreactiv ity. These data are compared with those obtained in a companion study carried out the same organs in two species of Equidae (Equus caballus and Equus asinus). Different patterns of immunoreactivities can be out lined in these domestic ungulates.