Nerve fibres in the parathyroid gland of the golden hamster (Mesocricetus auratus): immunohistochemical and ultrastructural investigations.

We investigated the morphology and the distribution of the nerve fibres in golden hamster (Mesocricetus auratus) parathyroid glands using antibodies to calcitonin gene-related peptide (CGRP) and substance P, and electron microscopy. CGRP-immunoreactive nerve fibres were densely distributed in the interstitial tissues and the capsules of the hamster parathyroid glands. Some nerve fibres were detected in close proximity of the parathyroid chief cells. The distribution pattern for substance P-immunoreactive nerve fibres was roughly the same as for CGRP-immunoreactive fibres. Ultrastructurally, we found numerous nerve fibres joining the blood vessels. Axon bundles were located adjacent to the smooth muscle cells of the arterioles. The axons formed structurally specialized neuromuscular junctions with the vascular smooth muscle cells. Some axons were in close vicinity to the parathyroid chief cells. These findings indicate that the hamster parathyroid gland contain CGRP and substance P, which may regulate the blood flow and the secretory activity of the gland.