Labels:text | screenshot | black | black and white | document OCR: S (Fig. 2.4) Prolactinomas or lactotroph cell tumou are the most common pituitary tumour nt of all accounting for approximately fifty per ce hours were such tumours. For many years, these tu er, with considered to be nonfunctioning; howe ith the the discovery of human prolactin, and v las become development of radioimmunoassays, it ctioning clear that most of these so-called nonfur pituitary tumours are prolactinomas.