A Histochemical Study of Sex Inversion Produced by Estradiol in Chick Embryos.

G O N A D A L inversion produced by sex hormones has been studied by many authors trying to understand sex differentiation and its hormonal control. The work of Dantchakoff (1935), Wolff & Ginglinger (1935) and Willier, Gallagher & Koch (1935), who studied sex inversion in genetically male chick gonads caused by the action of estrogens, as well as work done since then on birds and other vertebrates, dealt with the morphology of inverted gonads, while very few attempts have been made to analyse them functionally. Perhaps the most important work on this aspect has been that of Wolff & Haffen (1961), who demonstrated that inverted chick gonads are capable of producing feminizing substances. It seems well established that hormonal production by normal chick embryonic ovaries is localized in medullary interstitial cells as judged from their high content in lipids and cholesterol (Scheib, 1959; Narbaitz & Sabatini, 1963) and J5-3j8hydroxysteroid dehydrogenase (Narbaitz & Kolodny, 1964; Chieffi, Manelli, Botte & Mastrolia, 1964). It appeared to us of interest to know if cells with the same localization and histochemical characteristics are present in inverted gonads. Since at early ages these are undistinguishable from normal ovaries, their study was made possible through the help of simultaneous determination of genetic sex by study of the chromosomes.