of extra chromosome o Typically less muscularless body hair increased breast

of extra chromosome o Typically, less muscular/less body hair, increased breast tissue  due to lower testosterone production  Sexual differentiation occurs after the first six weeks of development  duct systems for both sets of sex organs are present + gonads o SRY mediates sexual differentiation because of TDF which causes gonads to produce testosterone  T then determines duct development o Mullerian duct  forms the fallopian tubes, uterus and upper part of vagina  Develops in absence of testosterone  Wolffian duct degenerates o Wolffian duct  forms the vas deferens, epididymis, seminal vesicle and ejaculatory duct  Develops in presence of testosterone  also promotes production of Mullerian-inhibiting factor (MIF)  Mullerian duct degenerates o Hermaphroditism occurs when external genitals are undetermined or in an intermediate form  due to hormonal irregularities during differentiation stage of development  Sex hormones belong to the steroid class of hormones  synthesized from cholesterol o Each have a four-carbon ring-structure  small chemical changes to base molecule causes profound consequences for effects of sex hormone  Males produce more androgens  testosterone  Released by testes and adrenal glands  Responsible for masculinization  females have 1/10 th amount  Levels surge prenatally during primary differentiation and at puberty during development of secondary sex characteristics  Females produce more estrogens and progestins  estradiol/estrone, progesterone  Released by ovaries  Estrogen levels surge during puberty to control maturation of reproductive cycle and breast development  Progesterone levels increase during pregnancy  Female hormones follow 28-day estrus cycle o Most hormones are peptides and therefore cannot readily cross the cell membrane  steroids are fat soluble and thus easily cross the lipid bilayer  Steroids act on intracellular receptors within the cytoplasm  directly affect gene expression  Different tissues express internal receptors differently, so respond to the effects of sex hormones differently o Ex. Breast tissue has a strong response to estrogens 