POSSIBLE RÔLE OF PROLACTIN DURING THE OESTROUS CYCLE AND GESTATION IN THE EWE

Stricker & Gruether (1928, 1929) were the first to observe that whole pituitary extracts could initiate lactation in pseudopregnant ovariectomized rabbits. Greatly assisted by the many advantages of the specific pigeon crop sac response for isolation and quantitative assay of the effective protein, Riddle, Bates & Dykshorn (1933) isolated it and named it 'prolactin'. Since this early work, prolactin has been shown to have an important luteotrophic rôle in many species. In this rôle it is usually associated with LH.In studying the part played by prolactin in reproductive processes, we have investigated its secretion throughout the oestrous cycle and during pregnancy in the sheep, and have studied the effects of replacement therapy in hypophysectomized and pituitary stalk-sectioned ewes.All the experiments have been carried out on ewes of