Prolactin induced mitotic activity in the anterior pituitary gland of the chick

The current investigation was undertaken to study whether mammalian prolactin can induce mitotic activity in the anterior pituitary gland in chicks. It was found that intramuscular injections of ovine prolactin (1.5 i.u. and 10 i.u. each daily per bird for 10 days) significantly increased mitotic frequency in the adenohypophysis of juvenile cockerels. It is suggested that ovine prolactin has a mitogenic action on the adenohypophysis of the male chicks and that the reaction may be dose-dependent.