metribolone and moxestrol

Administration of exogenous estradiol benzoate (EB) or an estrogen agonist, R2858, into eggs of snapping turtles caused all embryos incubated at male-producing temperatures to develop as females, whereas testosterone propionate (TP) caused 42% of the embryos to develop as females. Some of the embryos treated with EB, R2858, or TP also had hypertrophied oviducts. Neither dihydrotestosterone (DHT) nor cholesterol had any apparent effect on the sex determination of embryos incubated at male-producing temperatures. Injections of TP, DHT, the androgen agonist R1881, or cholesterol had no apparent effect on sex determination of embryos incubated at female-producing temperatures. Administration of estradiol antiserum or testosterone antiserum resulted in some individuals having undifferentiated or ambiguous gonads. Although both exogenous estrogens and androgens can induce embryonic gonads to develop as ovaries, the findings of this study indicate that estrogen is the female-inducing hormone and that androgens may feminize gonads via aromatization to estrogen. Furthermore, the results of the antisera injection suggest that endogenous steroid hormones may have a natural role in gonadal differentiation of reptiles with environmental sex determination.

Topics: Animals; Cholesterol; Dihydrotestosterone; Estradiol; Estrogen Antagonists; Ethinyl Estradiol; Female; Gonadal Steroid Hormones; Immune Sera; Male; Metribolone; Sex Determination Analysis; Sex Differentiation; Temperature; Testosterone; Testosterone Congeners; Turtles

It is firmly believed that sexual differentiation of the brain is linked with external genital differentiation in timing as an in utero event in the human. An extensive search for oestrogen, androgen and progestin receptors failed to show their presence despite adequate controls in cytosols from human fetal brain of gestational ages 14-20 weeks. It is possible that the receptors are present in levels so low that they are undetectable by present-day methods. Our results would indicate that hormonally influenced in utero brain sexual differentiation is most unlikely to occur as a mid-trimester event.

Topics: Animals; Brain; Brain Chemistry; Cytosol; Diethylstilbestrol; Estradiol; Estradiol Congeners; Estrenes; Ethinyl Estradiol; Female; Gestational Age; Humans; Ligands; Male; Metribolone; Pregnenediones; Progesterone Congeners; Rats; Receptors, Androgen; Receptors, Estrogen; Receptors, Progesterone; Sex Differentiation; Testosterone; Testosterone Congeners

Topics: Cytosol; Dexamethasone; Estrenes; Ethinyl Estradiol; Humans; Metribolone; Progestins; Promegestone; Receptors, Cell Surface; Receptors, Steroid; Skin