[Immunohistochemical studies on pituitary adenomas in Wistar rats. 1. Demonstration of ACTH, LH, neurophysin, oxytocin and vasopressin in the pituitary of Ico:WIST rats from chronic toxicity studies].

Spontaneous pituitary adenomas are common in certain strains of the laboratory rat. Investigations of Wistar rats of two years chronic toxicity studies revealed pituitary tumors in 50% of the females and 26% of the males. The morphology of the spontaneous changes in the pituitary gland was investigated with immunohistochemical and histological methods. The peroxidase-antiperoxidase (PAP) technique was used to localize different hormones (LH, ACTH) in cells of the pars intermedia and pars distalis as well as neurophysin, oxytocin and vasopressin the terminals of the classic neurosecretory system of the pars nervosa. The results show that most of the neoplasms were endocrinologically inactive chromophobe adenomas of the pars distalis.