Gonadal Differentiation Flashcards
What technique was used in mapping out sex chromosomes?
FISH
What is SRY protein?
Sex-determining region Y, DNA-binding protein that initiates testes development
What is SF-1?
Steroidigenic factor-1, transcription factor that is important for gonadal and adrenal development, reproduction, and production of anti mullerian hormone
What do mutations in SF-1 lead to?
A range of problems including adrenal insufficiency in 46,XY females (low androgens), and gonadal dysgenesis
What does translocation of SRY lead to?
46,XX males (SRY functional)
What does mutation of SRY lead to?
Mutation of SRY leads to 46,XY females (loss of SRY function)
What does the presence of androgens induce in males?
Prenatally induces genital differentiation, during puberty induces the development of secondary sex characteristics
What does the low amount of androgens allow for in females?
Female genital differentiation and the development of female secondary sex characteristics
What does it mean that the undifferentiated gonad is bipotential?
Has the potential to form testes or ovaries
What are mullerian ducts?
Paired ducts of the embryo that run down the lateral sides of the urogenital ridge. Formed due to levels of estrogen, not exposed to AMH or androgens
What do mullerian ducts form in females vs males?
In females, they will form the fallopian tubes, uterus, and the upper portion of the vagina. In males, they are lost
What is the default form of the gonad?
Female, without exposure or sensitivity to androgens, the gonad becomes a female gonad
What is the wolffian duct?
Paired organ also found during embryogenesis. In males it develops into the epididymis, vas deferens, and the seminal vesicle. They must be exposed to testosterone during embryogenesis
What is anti-mullerian hormone?
It is a member of the TGF-B family produced by sertoli cells and leydig cells to stabilize wolffian ducts
Does testicular differentiation or ovarian differentiation come first?
Testicular differentiation precedes ovarian development
What is amenorrhea?
Lack of menstrual cycle after age 16 or 3 missed periods. Possible sign of genetic, endocrine, or anatomic abnormalities –> GnRH deficiency, functional hypothalamic amenorrhea, hyperprolinactinemia.
What is Kallmann’s syndrome?
Adhesion molecule genetic mutation - no migration of gnRH producing cells to hypothalamus –> no sexual maturity –> don’t get correct location of release
What is functional hypothalamic amenorrhea?
Reduced GnRH pulse frequency and amplitude –> low FSH and LH, leptin (low levels), minor activation of HPA axis and incidences of psychological stress, strenuous exercise or poor nutrition
What is hyperprolactinemia?
Dopamine is not inhibiting prolactin release
What is menopause?
Ovary ceases to function at age 51 –> hot flashes, urogenital atrophy, osteoporosis, cardiovascular disease, many psychological issues
What is Klinefelter’s syndrome?
Male, XXY –> more than one X chromosome. Causes gonadal dysgenesis, low testosterone, sometimes no clear secondary sex characteristics. Occurs in 1/500 males. It is the most common form of male hypogonadism –> low androgens
What is Turner’s Syndrome?
Missing X chromosome. Gonadal dysgenesis, almost no estrogen or progesterone, no secondary sex characteristics, short stature, webbed neck, heading loss. Most often the father did not pass on sex chromosomes. Treatable with hormones.
What is intersex 46,XY?
Have testes, but genital ducts or external genitalia are not fully masculinized. May be caused by defect in testosterone secretion or androgen insensitivity syndrome.
What are defects in testosterone secretion?
May have SF-1 mutation or LHR mutation –> not a receptor problem. May lead to testicular dysgenesis, impaired T or AMH secretion, gonadal tissue not responsive, no T –> DHT conversion (may lack 5alpha reductase) –> DHT important for secondary sex characteristics
