Tyrosine-hydroxylase-immunoreactive nerve fibers in the separated capsule of the rat adrenal gland.

The present study applied the separated adrenal capsules of rats for wholemount immunocytochemistry and used tyrosine hydroxylase (TH) antibody as a marker for catecholamines. TH-immunoreactive nerve bundles without varicosities and fibers with varicosities were seen to run along or to encircle blood vessels entering the adrenal capsule from the outside, and then to run along a network of blood vessels in the intracapsular region. Also, the TH-immunoreactive nerve bundles and fibers were found to run along blood vessels in the subcapsular region. Some TH-immunoreactive nerve fibers and bundles with varicosities, unassociated with the blood vessels, were seen in the subcapsular region. In this region, TH-immunoreactive nerve fibers with varicosities were often seen to be closely associated with the cortical cells. Some TH-immunoreactive nerve fibers without varicosities were visible within the splanchnic nerve in the subcapsular region. The present study suggests that numerous catecholaminergic nerve fibers are associated with blood vessels forming a network in the superficial region of the rat adrenal gland.