Immunohistochemical demonstration of tenascin in human pituitary glands and adenomas.

The expression of tenascin in 8 cases of normal fetal and adult human pituitary glands and in 51 cases of human pituitary adenomas was investigated immunohistochemically with the use of polyclonal antibodies against human tenascin. The immunohistochemical study demonstrated that tenascin is expressed in both fetal and adult normal epithelial cells of the anterior lobe of pituitary glands and in tumor cells of pituitary adenomas, which suggests that tenascin is synthesized by normal pituitary cells as well as by pituitary adenoma cells. Plurihormonal pituitary adenomas, especially those producing 4 or 5 different hormones, tended to show the highest incidence of positive immunoreactivity for tenascin, suggesting that tenascin may be involved in the aggressive behaviour of plurihormonal adenomas.