Human pituitary tumours in organ culture with correlation to clinical data.

Out of 56 operated pituitary tumours 31 were hypersecreting growth hormone (GH), 12 hypersecreting prolactin (PRL), 2 hypersecreting ACTH and 11 tumours were chromophobe without secretion of hormone. One pituitary revealed normal conditions at the surgical exploration later confirmed at the renewed endocrinological investigation. 36 pituitary tumours have been explanted to in vitro culture: 20 tumours causing acromegaly, 9 porlactinomas, 2 ACTH-producing and 5 chromophobe adenomas. The higher the GH concentration was in vitro, the more active was the degree of acromegaly found clinically. GH hypersecreting tumours also secreted small amounts of PRL in vitro and the countary concerning prolactinomas. The GH/PRL ratio was individual for each tumour, GH or PRL hypersecreting. Tumour tissue revealed approximately the same characteristics in vitro, irrespective of whether taken from different regions of the tumour. A good correlation occurred in the secretion of PRL in vivo and in vitro, i.e. the higher the serum level of PRL the higher concentration of PRL found in the culture medium. Mitosis did not occur in any of the histological sections of more than 400 separate specimens. The increase in PRL in cultured specimens is probably due to the absence of a prolactin-inhibiting factor (PIF) during in vitro culture. On the other hand, the decreasing GH levels may be due to the absence of a GH-releasing factor. The results of the present study suggest an individual biology in each pituitary tumour.