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sex

sex. differences between males & females. Anatomy (& its development) Physiology (e.g., hormones) Behavior (sexually dimorphic behavior). Anatomy: A hermaphrodite is an organism that posses both male and female genitalia. Most common in invertebrates Simultaneous (slugs, earthworms)

lilah-schroeder
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sex

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  1. sex

  2. differences between males & females • Anatomy (& its development) • Physiology (e.g., hormones) • Behavior (sexually dimorphic behavior)

  3. Anatomy: A hermaphrodite is an organism that posses both male and female genitalia. Most common in invertebrates • Simultaneous (slugs, earthworms) • Sequential (clown fish) 'reclining hermaphrodite', a 1st-century BC sculpture

  4. Anatomy: Sex determination Every grandma wants to know: “Will it be a boy or a girl?” What determines the sex of the baby varies across species • Environmental • How hot it is (turtles, alligators) • Social • Is there a mom here? (clown fish) • Genetic • In humans & other mammals:

  5. A sperm fertilizing an egg (ovum) Sex determination systems XX XY Gamets (sperm & egg) are made by the gonads (testis, ovary)

  6. Males Chromosomes Chromosomal sex Y chromosome: Sry Gonads (testes) Gonadal sex Prenatal Hormones Hormonal sex Brain structures Internal genitalia Brain sex External genitalia Genital sex

  7. Gonads: testis, ovary produce gametes (sperm, ovum) secrete hormones (testosterone; estrogen, progesterone).

  8. Conception: Chromosomal sex is determined (XX, XY) 7-8 weeks embryo: Undifferentiated gonads can develop into phenotypic male or female gonads Sry (a gene in Y chromosome): leads to male gonad development (testes) Hormones secreted by testes lead to development of Male internal and external genitalia

  9. - Fallopian Tubes - Uterus - Inner Vagina - Epididymis, vas deferens, - seminal vesicles, - prostate - Clitoris, - Labia, - Outer vagina: - Penis - Scrotum Internal Genitalia External Genitalia: Internal Genitalia:

  10. Testosterone Development of external genitalia in males 5 alpha-reductase DHT(deihydrotestosterone) Development of penis and scrotum 16-week old fetus

  11. - Clitoris, - Labia, - Outer vagina: - Penis - Scrotum External Genitalia:

  12. Sexual differentiation of the brain TESTOSTERONE aromatase • Sensitivity to Test.osterone • Spinal cord centers • Hypothalamic differentiation • Defeminization ESTROGEN Masculinization of the brain MALE

  13. Sexual differentiation of the brain TESTOSTERONE aromatase • Sensitivity to Test. • Spinal cord centers • Hypothalamic differentiation • Defeminization ESTROGEN Masculinization of the brain FEMALE Circulating maternal estrogen? Attached to alpha-fetoprotein, does not get into the fetus brain

  14. Androgen Insensitivity Syndrome Chromosomes male Y chromosome: Sry Gonads (testes) male Prenatal Hormones male Brain structures FEMALE No Receptors for Androgens Internal genitalia External genitalia

  15. Adrenogenital Syndrome Chromosomes female Gonads (ovaries) female Prenatal Hormones male Androgen Hormone Brain structures MALE Internal genitalia External genitalia

  16. Sex chromosomes abnormalities Turner syndrome (X0) Klinefelter syndrome (XXY)

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