Occurrence and coexistence of some neuropeptides in nerve fibers supplying the bovine ovary and its extrinsic blood vessels.

Single- and double-labelling immunofluorescence was applied to investigate the occurrence and coexistence of vasoactive intestinal polypeptide (VIP), calcitonin gene-related peptide (CGRP) and substance P (SP) in nerve fibers supplying the bovine ovary as well as its extrinsic blood vessels. We also studied the coexistence of these neuropeptides with tyrosine hydroxylase (TH) and neuropeptide Y (NPY) to determine features of "chemical coding" of nerve fibers innervating this organ. The bovine ovary was found to be supplied by VIP- and SP-immunoreactive (VIP- and SP-IR) nerve fibers. No intraovarian CGRP-IR nerve terminals were detected. Immunoreactivity to VIP was shown in a moderate number of nerve fibers occurring in all ovarian regions - ovarian hilus, cortex and medulla. VIP-IR nerves were found to innervate blood vessels and ovarian follicles, especially primordial and primary ones. Immunoreactivity to SP was detected only in solitary intraovarian nerve fibers which were also encountered in all ovarian regions, but with special preference to ovarian medulla, where they innervated blood vessels. SP-IR nerve fibres were sometimes observed in close vicinity to primordial and primary follicles. Double-labelling immunofluorescence revealed that some VIP-IR nerve fibres supplying intraovarian blood vessels were simultaneously TH- or NPY-IR. Small numbers of VIP-IR fibres contained immunoreactivity to SP. All SP-IR nerve terminals were TH-or NPY-negative. The ovarian artery as well as arteries of the paraovarian plexus were moderately supplied with VIP-, or by single CGRP- or SP-IR nerve fibres. Veins were innervated by only solitary nerve terminals containing these neuropeptides. The following patterns of coexistence were determined in nerve fibres supplying the investigated blood vessels: VIP, VIP/CGRP, VIP/SP, CGRP/SP, VIP/NPY. No distinct differences in the innervation of the ovary and its extrinsic blood vessels between juvenile and adult cows were found.