Hormones and structural development / by Charles R. Stockard.

  • Charles Rupert Stockard
Date:
[1927]
Catalogue details

Licence: In copyright

Credit: Hormones and structural development / by Charles R. Stockard. Source: Wellcome Collection.

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    a rooster and may grow spurs and actually behave in many ways like the male. If similar operations be per¬ formed on ducks or other birds the results are very closely the same. It is of considerable interest to note that the removal of gonads from the mammal causes both sexes to assume a state quite like the usual female type, while the removal of the gonads from birds on the contrary causes both sexes to develop plumage of the usual male type. In both groups, therefore, the characteristics of the operated individual approach in general the homozygous sex which has in its cells the two X-chromosomes instead of one. In the mammals this homozygous two X-chromosome con¬ dition is in the female and among the birds it is in the male sex. This chromosome arrangement is supposed to be of prime importance in determining the sex of the indi¬ vidual at the time the egg is fertilized by the spermatozoon. Among the invertebrates there are some beautiful examples of sex dimorphism, the male and female being widely different in both form and color, yet this seems entirely independent of the gonads. In some insects the male, for example, may have wing color entirely different from the female, or one sex may be wingless while the other is winged. The removal of the gonad even from the embryo of the invertebrate seems to have no effect whatever on the expression of either body form or color. It is, therefore, probable that there is no internal secre¬ tion from the gonad of the invertebrate comparable to that in the vertebrates, and here sex dimorphism is regulated in a manner entirely different from that of the vertebrate. TRANSPLANTATION AND INJECTION OF GONADS The action of the gonadal secretions has been exten¬ sively studied by transplantation experiments. We some-
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