Identification of neural profiles containing vasoactive intestinal polypeptide, acetylcholinesterase and catecholamines in the rat thymus.

Sympathetic and parasympathetic innervation of the rat thymus is described using immunohistochemical, fluorescence histochemical and histochemical methods. Sympathetic innervation was found to enter the gland with the vasculature and to be distributed mainly in the subcapsular and corticomedullary junctional areas of the cortex. The parasympathetic innervation was also found to enter the gland with the vasculature, but was distributed to both cortex and medulla. Acetylcholinesterase-positive staining cells were seen in the medulla. Ideas about the function of thymus innervation are discussed.