Effect of Estrogen on Sexual Differentiation of the Medial Preoptic Area in Chicken.

概要

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To investigate the effect of estrogen on the formation of the medial preoptic area (MPA) in chicken, histological changes of MPA were studied by using adult chickens treated with 1mg estradiol benzoate at 5th, 10th and 15th day of incubation. There were no differences in the volume and the total number of perikaryons between sexes in estrogen-untreated chickens. However, male MPA included more perikaryons of a large size (diameter more than 10μm) than that of female, indicating the sexual differentiation of MPA in chicken. In estrogen-treated chickens, the numbers of large perikaryons in male groups treated with estrogen at 5th and 10th day of incubation decreased and approached to those of female groups which did not change by the difference of estrogen-treated days. It had been proved in the previous experiment that the male groups used in this experiment were not able to show the mating behavior. These findings raise the possibility that one of the causes involved in the disappear of male mating behavior may be the inhibition of MPA formation into the normal male type by estrogen.
日本家禽学会の論文