Thursday Oct 21

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Thursday Oct 21 Short lecture then video
Gender Trouble Please drag yourself in
important information today. GO SOX!!!
We are all lucky that no game is scheduled for
Monday night! Study hard for Tuesdays exam.
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Abnormalities of Sexual Development 1. Genetic
abnormalities that interfere with receptor
development Androgenic Insensitivity
Syndrome Persistent Mullerian Duct Syndrome 2.
Abnormalities in sex chromosomes Turners
Syndrome (XO) 3. Hormonal abnormalities in other
glands Adrenogenital syndrome -------------------
---------------------------------------------- 1.
Normal development with abnormalities produced by
surgical error during circumcision
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• Surgical error - Ablatio Penis
• accidental removal of penis during
  circumcision
• Case Study
• 2 normal identical twin boys born (60s)
• during circumcision, error made on one other
  remained normal
• doctors said castrate, create a vagina, raise as
  female, give hormones later (the 60s -
  behaviorism)
• at age 12, described by doctor as appearing and
  acting as normal girl
• Was this correct?

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• Surgical error - Ablatio Penis
• accidental removal of penis during
  circumcision
• Case Study
• He did not feel like a normal girl.
• at 14, decided to be a boy - had surgery and
  androgen treatments, breast removal creation of
  male anatomy
• strictly heterosexual male sex
  behavior/interests
• later married

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• Biological correlates of sexual development and
  behavior
• In animals, reproductive behavior is clearly
  organized by effects of presence/absence of
  androgens
• 1. The Sexually Dimorphic Nucleus of the Preoptic
  Area of the Hypothalamus (SDN-POA)
• In brain of male rats, preoptic area of
  hypothalamus is much larger than in females.
• lesions of preoptic area known to reduce
  copulatory behavior in adult male rats reduce
  ovulatory cycles in adult female rats temporary
  effects
• remove androgenic influences at birth in male
  rats, small POA develops and they direct sex
  activity towards males. Apply androgenic
  influences in females at birth, large POA
  develops and sex activity directed at females.
• Human males have an anterior hypothalamic
  nucleus (INAH-1) that is twice as large and has
  twice as many cells as females.

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• Hormonal studies - Rodents, pigs, dogs
• remove perinatal influence of androgens and
  males develop female behavioral pattern
• Give androgens to females during perinatal
  period- they later prefer females

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• Biological correlates of sexual development and
  behavior
• 2. Spinal cord differences related to control of
  muscles at base of penis
• motoneurons in spinal cord (SNB spinal nucleus
  of the bulbocavernosus) that control BC penile
  muscles 200 SNB neurons in male rats, many
  fewer in female rats
• a few days before birth, male numbers of SNB
  female numbers. Maintained by androgens in males
  some die off in females
• Humans BC muscles are larger in men and they
  have more corresponding motoneurons. In women,
  these muscles contrict the vagina.

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• Biological correlates of sexual development and
  behavior
• 3. Social influences on development of rats SNB
  neurons (work by Dr. Celia Moore, UMass Boston,
  Psychology)
• necessary for rat dams to lick the anogenital
  region of newborn pups to stimulate urination and
  defecation
• male rat pups smell different due to metabolites
  of androgens in their urine. Dams lick males
  more when they detect this smell. Maternal
  licking stimulates development of the muscles and
  the SNB neurons in the spinal cord of males.
• Thus, dam treats pup differently based on sex
  and the different treatment masculinizes certain
  aspects of male spinal cord and SNB. In female
  pups, less licking feminizes development of SNB.

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• Influences on sexual orientation
• Homosexuality has been observed in several
  species sheep, swans, gulls, dolphins, apes,
  monkeys humans
• In humans
• LeVay (1991) reported a preoptic area group of
  neurons that was larger in men than women and
  larger in heterosexual than homosexual men.
  (autopsy of brains of straight and gay people
  that died of AIDS)
• Very controversial!
• Being gay, may cause difference social
  influences may cause differences - chicken or egg
  problem

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• In humans
• Genetic studies
• Identical male twins - if one gay, 52 of time,
  other twin is gay
• 22 match in dizygotic twins (related like
  brothers)
• possible that a gene on the X chromosome is
  important to male sexual orientation
• however, having the same genes does not always
  mean having the same sexual orientation

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• Hormonal studies - human adults
• heterosexual and homosexual men do not differ in
  hormone levels
• removal of male hormones (post cancer surgery)
  in adulthood does not change sexual orientation
• But this does not address hormone levels at
  earlier critical stages of development.
• At this time, genes, hormonal environment, and
  social experiences all appear important to human
  sexual orientation.