The Functions of the Corpus Luteum.--I. The Mechanism of Oestrus Inhibition

The methods by which the action of the corpus luteum can be studied have recently become greatly extended. It is possible to eliminate the corpora lutea by X-ray sterilisatioin, while, on the other hand, the production of luteal tissue may be intensely stimulated by the administration of anterior pituitary extracts. It is also possible to obtain extracts of corpora lutea which will substitute at least one function of the corpus luteum. As test objects, the vaginal smear test for œstrus inhibition, the placentoma test for the sensitization of the uterus, and the experimental study of the rabbit mammary gland, provide easy means of ascertaining luteal activity. It is intended, in the series of reports of which the present is the first, to record an investigation into the physiology of the corpus luteum carried out by means of these various techniques. In previous paper (Parkes and Bellery, 10, 11) the evidence that the corpus luteum has an œstrus-inhibiting action was fully discussed, and a method of preparing an œstrus-inhibiting extract of the organ was described. In the present paper various lines of work bearing on this problem will be recorded It has been pointed out before (Parkes, 8) that, since obliteration of the corpora lutea in the ordinary unmated cycle of the mouse does not affect the length, the corpora lutea under these conditions can have neither an œstrus-promoting nor an œstrus-inhibiting action. After sterile copulation, however, the corpora lutes of ovulation persist and interval before the next œstrus period is prolonged from 4 days to about 12 days. In this paper it is hoped to be able to demonstrate the dependence of the latter upon the former event.