Abstract
Conclusions
The presented data indicate that estrogens produce sex reversal in male salamanders, while testosterone propionate exerts no corresponding influence upon genetical females. As in adult animals, the secondary sex characters respond also in the larval salamanders to the administration of sex hormones. The female hormone stimulates slightly the larval Mullerian ducts, and the male hormone causes an extensive and very precocious stimulation of the larval Wolffian ducts and cloacal glands. It is remarkable that the estrogens affect most profoundly the male gonads and the testosterone the male secondary sex characters. The hormones do not induce original formation of gonoducts; they stimulate only the secondary (functional) enlargement of parts of ducts already present. It has been shown by means of parabiosis that the testes of males release some inductive substance which inhibits the development of the ovaries of female cotwins and indirectly may cause some genetic females to continue development in a male direction. 6 On the other hand, in the male-female parabiotic combinations there is no precocious stimulation of either gonoducts or cloacal glands. These fundamental differences in the observed reactions prove that the crystalline sex hormones used in this experiment cannot be identical with the substances which normally act as inductors of sex differentiation.
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