DISTINCT PREGANGLIONIC NEURONS INNERVATE NORADRENALINE AND ADRENALINECELLS IN THE CAT ADRENAL-MEDULLA

Calretinin immunoreactivity was present in a subset of preganglionic n eurons retrogradely labelled from the cat adrenal gland. Overall, one- third of adrenal preganglionic neurons showed calretinin immunoreactiv ity, and their proportion increased in the more caudal spinal cord seg ments. Calretinin-immunoreactive nerve terminals were prominent within the adrenal gland, but were found only in areas of noradrenergic chro maffin cells (approximately one-third of the area of the adrenal medul la). Synaptophysin immunoreactivity was used to label terminals with a nd without calretinin immunoreactivity. Nerve terminals lacking calret inin immunoreactivity were present among the adrenergic chromaffin cel ls and also comprised 20% of the nerve terminals innervating noradrene rgic chromaffin cells. Calretinin immunoreactivity thus labels a subpo pulation of cat adrenal preganglionic neurons that innervate the norad renergic chromaffin cells.