Effects Of Estrogen And Progesterone Upon The Genital Tract Of The Ewe

STERILITY in ewes has not received a great deal of study, probably because of their relatively small individual value and the customary method of handling them. A large number of ewes, however, are marketed annually after failing to produce lambs for one, or in the case of very valuable ewes, for two years. Careful studies have been made of the changes occurring in the genital tract of the ewe during the different phases of the estrual cycle. Indications of the effects of the twohormones of the ovaries, estrogen and progestin, may be obtained from these studies, but their effects cannot be separated. Aclearer understanding of the function of each of these hormones would be of decided valueif it could be applied to the correction of sterilityand the maintenance of fertility in the ewe. This article reports a study in which an attempt has been made to determine, more accurately, the roles played by these two endocrinesubstances in the reproductive tract.