Studies in the effects of estrogen on the development of reproductive organs in the chick embryo as well as in the male chick after hatching, mainly histological

These studies have been carried out to test microscopically the effects of the estrogen on the development of reproductive organs of the chick embryo or chick itself. As estrogen, "Ovahormone Benzoate" (estradiol benzoate) was used. Three kinds of experiments were performed. The first was to inject the hormone into the egg during incubation, the second was to inject it in the breast muscle of the female fowl before ovulation (the chicks hatched from the eggs laid by the female fowl were tested in the experiments), and the third was to inject it (hormone only or hormone mixed with albumen of the same volume) to the chick intra-muscularly at the first feeding after hatching. The dose of estradiol benzoate were 2,000-10,000 I. U. in an egg, 50,000-500,000 I. U. in a female fowl and 50,000-500,000 M. U. in a male chick. These embryos were dissected on the nineteenth day of incubation and chicks were killed on about seventh day after finishing the administrations of the hormone. All of embryos and male chicks were examined under a binocular dissecting microscope to observe changes of development in the reproductive glands, Mullerian and Wolffian ducts. Results obtained on macroscopic observation in the first and the second cases were already reported by Tsuda, Oda and Tange (1955). Almost the same results were obtained in the third case. They may be summarized as follows : The left testis of the male was markedly altered in form and structure, appearing most often as a flattened ovary-like body. The development of Mullerian duct was observed.Results obtained on histological observations in these three experiments may be summarized as follows : (1) Some of the left testes had the ovarian cortex developed in the periphery of the testicular tissues. (2) The right testes had the tendency of the shrinkage of the whole tissues. (3) Melanin pigments sometimes appeared in the first or the second case. These were mainly found here and there in the interstitial tissues of the testis (4) By Dublin application of the Bodian method, these were recognised to be melanin pigments. (5) In an ovary of the second case, the development of the ovarian cortex seemed to remain in an atrophic state. (6) Mullerian duct was occasionally preserved and stimulated to develop, and by the influence of the estrogen, mucous coat (endometrium) of it was apt to extend. (7) A slight inhibitory action was sometimes observed on the wolffian duct