Physiology of Reproduction Flashcards
What determines genetic sex?
Chromosomes. XX or XY
What determines gonadal sex?
Testes or Ovaries
What determines genital sex?
External genitalia which is influenced by hormones
What is SRY?
Sex determining region of the Y chromosome
What is ovary development dependent upon?
The presence of TWO X chromosomes
What happens with the loss of a single X chromosome as in Turner’s syndrome?
Loss of one X chromosome results in ovarian dysgenesis but not loss of female ducts or genitalia
What occurs in meiosis I?
Chromosomes duplicate and exchange genetic material. Results in haploid numbers of duplicated chromosomes
What occurs in meiosis II?
Daughter cells have haploid (1N) chromosomes with the segregation of sex chromosomes providing a mechanism of sexual dimorphism.
What does sperm production require?
Reduced temperature
Is gonadal sex hormone dependent?
NO. It cannot be as the gonads make the hormones.
How is the decision for the progression to female genital structures made?
It occurs when there is no androgens present. Presence of androgens will influence male structure development.
What develops into seminiferous tubules, spermatogonia, sertoli cells, leydig cells?
Medulla
What develops into secondary sex cords, oogonia, theca cells, granulosa cells?
Cortex
What is the function of testosterone in regards to the ductal structures?
Keeps the Wolffian ducts
What is the function of AMH in regards to the ductal structures?
Degrades the Mullerian ducts
What happens if neither AMH nor testosterone are present?
The Mullerian ducts will remain and the Wolffian ducts will be lost resolution in a female.
What is the function of TDF?
It directs the development of the testes
What is the function of DHT?
It is more potent of an androgen than testosterone and it causes male genitalia development via androgen receptors.
What is the function of 5alpha-reductase?
Converts testosterone to DHT
What is the chromosome state of Turner’s Syndrome?
XO
What are the gonads/ducts/genitals found in Turner’s syndrome?
No gonads (only streak)
Mullerian
NO Wolffian
External female genitals
What is male pseudohermaphroditism?
Testes are present with external female genitals
What is female pseudohermaphroditism?
Ovaries are present with external male genitals
What causes male pseudohermaphroditism?
Androgen resistance
What causes female pseudohermaphroditism?
Excess androgens
What is the chromosome state found in androgen resistance?
XY
What are the gonads/ducts/genitals found in androgen resistance (AKA testicular feminization)?
Testes
NO Mullerian
NO Wolffian
External female genitals
What is the chromosome state found in 5alpha-hydroxylase deficiency?
XY
What are the gonads/ducts/genitals found in 5alpha-hydroxylase deficiency?
Testes
NO Mullerian
Wolffian
External can be male/female or both
What is the chromosome state found in Klinefelter’s Syndrome?
XXY
What are the gonads/ducts/genitals found in Klinefelter’s Syndrome?
Dysgenic Testes
NO Mullerian
Wolffian
External male genitals
What is the function of aromatase?
Converts testosterone into estrogen
What is testosterone found as in the plasma?
45% is bound to SHBG (sex hormone binding globulin)
55% bound to albumin and corticosteroid-binding globulin (CBG)
2% is free – biologically active and may diffuse into cells
What does testosterone affect directly?
Differentiation of the epididymus and vas deferens
Larynx
Skeleton
Increases abdominal visceral fat
Increases muscle mass
Increases RBCs
What does testosterone affect indirectly via E2/DHT?
Sperm production
Beard growth
Penis/scrotum development
Male pattern baldness
What are some treatments for prostate cancer and how are they effective?
5alpha-reductase inhibitors as prostate tumors are often DHT dependent
