week 9 Flashcards
(39 cards)
what are the 4 development stages of sex organs?
- Genetic Sex (XX, XY)
- Gonads(Testis/Ovaries)
- Sex Organs (Organizing Effects)
- Maturation (Organizing and Activating Effects)
What determines genetic sex?
If a boy child is born it is depended on the sperm.
Every egg has an X sex chromosome; a sperm can have either an X or a Y sex chromosome. If the sperm that fertilizes your egg has an X chromosome, you’ll have a girl; if it has a Y chromosome, your baby will be a boy.
Explain the development of gonads.
0-6 weeks → sex organs are undifferentiated
Undifferentiated gonads
Undifferentiated precursor tissue(rise to the sex organs):
Müllerian ducts (female)
Wolffian ducts (male)
Gonads (testes/ovaries) are the first to be determined
Important for production of sperm/ova and hormones
SRY(sex regsion determone on the Y chromosome) gene on the Y chromosome causes gonads to become testes
explain the Development ofOrganizing Effects of Sex Organs.
Becoming Female:
Müllerian system: The embryonic precursors of the female internal sex organs (fimbriae, fallopian tubes, uterus, inner 2/3 of vagina)
Associtated with the development of the female sex organs
Becoming Male:
Wolffian system: The embryonic precursors of the male internal sex organs (seminal vesicles, epididymis, vas deferens,)
Associtated with the development of the male sex organs
Müllerian & Wolffian are determined by Sex Hormones
what are the organizing effects and activating effects of hormones on to sexual differentiation? (Pre and post natal development)
Organizing effects
Sex hormones during prenatal development determines structure of sex organs and brain.
while the fetus is developing in the womb exposure to certain hormones will determine the structure of the sex organs, wheter Müllerian or Wolffian will be developed
Postnatal development at puberty determines other sexually dimorphic features (e.g., breast development and dropping of testes)
* Long lasting effects, lead to the organizing of the organism
Only occur during a specific sensitive period
Activating effects
Sex hormones activated during postnatal stage, e.g. sperm production, erection and ejaculation, ovulation, sex drive
More short term effects - cyclical
what are 2 steroid hormones?
Androgens = testosterone & dihydrotestosterone
Estrogens = estradiol
Their Actions:
Bind to membrane receptors to exert quick effects
Activate proteins in the cell
Alter expression of chromosomes to turn genes off/on.
What are the organizing effects of sexual development, and when do sexual organs start to differentiate?
Organizing Effects: Determination of internal and external sex organs
7-8 weeks → precursor tissue starts to differentiate, based on which hormones the fetus is exposed to
2 precursor tissue systems:
Mullerian system - female tissue
Wolffian system - male tissue
What are AMH/MIH?
Anti-mullerian hormone (AMH)/ mullerian inhibiting hormone (MIH)
Inhibits Müllerian system
Androgens (testosterone, and metabolite dihydrotestosterone)
Ensures development of Wolffian system
In depth, describe what the “male” and “female” hormones activate and organize.
Testosterone (“male” hormone) Androgen Organizing: facial and body hair, lowers voice, muscular development, genital growth Activating: sex drive, reproduction Estradiol (“female” hormone) Estrogen Organizing: breast development, lining of uterus, body fat deposition, maturation of female genitalia, Activating: sex drive, reproduction
Do females only produce estrogen, and do males only produce androgen?
Both males and females produce both androgen and estrogen
One generated less than the other based on the gonads
(testes - produces more androgens and less estrogen)
(ovary - produces more estrogen and less androgen)
What is considered normal for sex chromosomes for males and females?
Typical”
XX(female) OR XY(male) = Dichotomy
however… there are “shades of gray”
what is XX Male Syndrome?
XX sex-reversal
1/25,000 newborn males
Genetic sex is “female”(XX)
SRY is translocated to X chromosome
Y sequences usually located on the distal tip of the paternal X chromosome, something going on with respect to the sperm that is contributing to the development of the fetus
Male gonads (i.e. testes) are formed b/c the SRY gene is present
Identify with and physically look male
Shorter than average, less hair, gynecomastia, hypogonadal, infertile
They are missing all of the other genetic material that is commonly located on the y chromosome to contribute to these male typical features
What is XXY, Klinefelter Syndrome
1/600 newborn males
Additional X from mother’s egg or father’s sperm
Male newborn with extra X chromosome
Range in presentation of symptoms; later diagnosis
Can be mild to the point they are not diagnosed until teen years
75% never diagnosed, they only end up reaching a diagnosis if let’s say you know they’re trying to conceive
Taller than average, hypogonadal, infertile, abdominal fat, low muscle tone
Additional: metabolic syndrome(elevated adipose tissue - thick waistline, high levels of glucose), autoimmune disorder, autism spectrum
What is Androgen Insensitivity Syndrome (AIS)?
Genetic sex is “male” (XY)
Receptors do not respond to androgens or they do not have enough receptors to respond to androgens
AIS can range from complete (external genitalia feminized) to partial (partial genitalia masculinized) to mild (masculinized)
Internal testes/No ovaries or uterus
Hypogonadal – Shallow vagina
Infertile
What is Persistent Mullerian Duct Syndrome?
Genetic sex XY
Extremely rare (prevalence unknown; 250 reported cases in medical literature)
Failure to produce AMH or no receptors for the hormone
Genetic variation in AMH gene –inherited autosomal recessive gene, if you present with two of these recessive genes, then you will present with persistent Mullerian Duct Syndrome
Present with female and male internal sex organs
Both Mullerian system & Wolffian system develop
Undescended testes
Underdeveloped uterus
Hermaphroditism
Infertile
What is Turner’s Syndrome?
1/2500 newborn females
Genetic sex X (aka X0)
Either entire X, or partial X chromosome is missing
Result of defective sperm
Gonads do not develop (non-working ovaries)
Internal and external organs are female
No estrogen, puberty is induced
Poor breast development, short stature, broad chested, webbed neck
Other: learning disability, increased risk for CVD)cardiovascular disease), immune disorders
What is Congenital Adrenal Hyperplasia (CAH)?
1/15,000 newborn females (classic CAH)
Genetic sex is “female” (XX)
Autosomal recessive disorders –dysregulation of the adrenal glands
CAH babies are exposed to high androgen levels during development
Mullerian system activated, but external organs are “intersex”or “ambiguous”
For people with CAH, what does their behaviour look like?
CAH - Masculinization of Behavior
Early research: Ehrhardt (1975)
CAH showed no interest in jewelry, make-up
Preference for functional clothing > than dresses
They were more tomboyish
Low interest in infant care, weddings, marriage, dolls
40% of CAH women were straight and 37% identified as lesbian or bi-sexual (Money Swarts & Lewis, 1980s)
What do sex hormones do during prenatal development?
Determines structure of sex organs and brain
Postnatal development at puberty determines other sexually dimorphic features
Long lasting effects
Sensitive period
What are organizing effects of hormones on the brain?
Sexual dimorphism of hypothalamus largely a result of hormone exposure
No such thing as “male” brain and “female” brain
More differences within sex groups rather than between
How does hormones control sexual behaviour … in rats?
Sexually, male rodents are meant to mount the female rodents while they take an arched-back position called lordosis
What are Androgen exposure and organizing effects on sexual dimorphic behavior?
Behavioral defeminization - suppression of female neural circuits to prevent female behavior, prevent the lordosis pose
Behavioral masculinization - stimulation of male neural circuits to promote male behavior, prevent (*I think it should be promote not prevent) the mounting pose
How do sex hormones influence the development of the brain in rodents?
In rodent sex hormones influence development of the brain, even after birth so in rodents testosterone produces masculines effects during the last days of pregnacy and a few days after birth, provided a model to test the effects of hormone exposure
What happens in rodents when their ovaries are removed. (explain all 4 studies)
In study 1 rodents are born, ovaries are removed they are not exposed to anything, when they are fully grown they are ingested with estradiol and progesterone
These females take on lordosis posture
Activational effect of estradiol and progesterone
In Study 2 rodents are born, ovaries are removed they are not exposed to anything, when they are fully grown they are ingested with Testosterone
These females do not take on male behaviour
No activating effects from testosterone
In Study 3 female rodents are born, ovaries are removed and immediately after birth they are injected with estradiol and progesterone
Nothing happens
Defeminization effects with estradiol and progesterone fails to facilitate female secual beh.
In Study 4 female rodents are born, ovaries are removed and immediately after birth they are injected with Testosterone, then later on in birth they are exposed to testosterone again
They display mounting behaviour, male beh.
