Abstract
Experiments were begun in the spring of 1924 for the purpose of analyzing the sex potentialities of developing chick gonads by transplanting them to the vascular chorio-allantoic membranes of host chick embryos. In these experiments the circulations of the host embryo and the sex graft are related in a manner which is essentially similar to the relations existing between twin embryos in cattle. 1 In this analysis several important problems arise. It may be possible to determine first how early in development the sex potencies of the gonads and their laterality are fixed; secondly, whether these original sex potencies may be modified or inverted by transplanting the gonadal primordia during the morphologically indifferent stage to host embryos of opposite sexes; thirdly, the behavior of sexually differentiated right and left ovaries and testes when implanted to male and female host embryos.
The method employed was essentially the same as previously reported. 2 The Wolffian body with its associated sex gland and adrenal was isolated with the aid of a binocular microscope from a donor embryo at various periods of incubation as indicated below. This isolated complex was then implanted to the chorioallantoic membrane of a host chick embryo. In this manner the right and left gonads were implanted to male and female host embryos. The transplantations were made in all cases upon host embryos during the ninth day of incubation, and permitted to grow for an average period of nine days. The grafts were then removed and prepared for histological examination.
The sexual glands used in transplanting may be grouped into two stages of development or differentiation : (1) before sexual differentiation, that is, during the morphologically “indifferent stage”; and (2) after sexual differentiation.
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