The effects of embryonic treatments with gonadal hormones on sexually dimorphic behavior of chicks.
In order to study the role of sex steroids in the differentiation of chick behavior, two groups of experiments were carried out. The first part of the study documented sexual dimorphisms in three behavioral measures in chicks: open-field activity, flocking response, and masculine sexual behavior activated by testosterone (crowing, waltzing, and mating attempts). In the second part, possible organizing influences on these sexually dimorphic behaviors were examined. Male and female embryos were injected with estradiol benzoate (EB) or testosterone propionate (TP). Treatment of males with EB or TP demasculinized all three behaviors. None of the steroid treatments had any effect on the behavior of the females. Plasma testosterone levels of the chicks were not affected by any of these treatments, either before or after testosterone activation. Comb weight was reduced by treatment of male embryos with EB and increased by TP in female embryos, which suggests different mechanism for the development of somatic and behavioral characteristics. The results suggest that exogenous T or E given embryonically can exert similar effects on both sexual behavior and nonreproductive activity of chicks.
Sayag
N
N
Department of Animal Science, Faculty of Agriculture, Hebrew University of Jerusalem, Rehovot, Israel.
Robinzon
B
B
Snapir
N
N
Arnon
E
E
Grimm
V E
VE
D000818:Animals; D002642:Chick Embryo; D002645:Chickens / Q000502:physiology*; D004958:Estradiol / Q000494:pharmacology*; D005260:Female; D008297:Male; D012727:Sex Characteristics; D012726:Sexual Behavior, Animal / Q000187:drug effects*; D013739:Testosterone / Q000494:pharmacology*
D013739:Testosterone; D004958:Estradiol