Chapter 22 Flashcards
The gonads have the dual function of…
Gametogenesis and secretion of sex hormones
_____ are steroid hormones that are masculinizing in their action
Androgens
_____ are steroid hormones that are feminizing in their action
Estrogens
This steroid hormone has special functions in preparing the uterus for pregnancy
Progesterone
This polypeptide hormone is released to loosen the ligaments of pubic symphysis and soften the cervix
Relaxin
This polypeptide inhibits FSH secretion
Inhibin B
These anterior pituitary gonadotropins aid in the secretory and gametogenic functions of the gonads
FSH and LH
What is the difference in gonadotropin secretion between males and females?
In males secretion is non-cyclic, in females secretion is periodic and necessary for menstruation, pregnancy, and lactation.
This locus on the Y chromosome contains the testis-determining gene product
SRY (sex-determining region of the Y chromosome)
Which drug arrests mitosis at the metaphase?
Colchicine
What region of the X chromosome in females turns off one of the other X chromosomes?
X-inactivation center (probably via CTCF)
What structure does the inactive X chromosome form in female cells?
Barr body (usually near the nuclear membrane)
What embryological structure does the gonad develop from?
A genital ridge of tissue near the adrenal gland.
How long is the genital ridge identical between the two sexes?
Six weeks of development
What happens to the genital ridge in males between the seventh and eighth week of development? What cell types appear? What hormones are released?
The medulla develops into the testis, and the cortex regresses. Leydig and Sertoli cells appear and testosterone and MIS are secreted.
What happens to the genital ridge in females between the seventh and eighth week of development? What hormones are released?
The cortex develops into an ovary, and the medulla regresses. The embryonic ovary does not release any hormones.
What duct system develops in an embryo destined to be a female? What about a male?
For females, the mullerian duct system develops into uterine tubes (oviducts) and a uterus.
For males, the wolffian duct system develops into the epididymis and vas deferens.
What happens to the urogenital slit in embryos destined to become female? Male?
In males, the urogenital slit disappears; for females, the urogenital slit remains open.
What are the effects of androgen exposure to an embryo?
In rats, monkeys, and humans masculinizing effects on behavior appear. However, in humans and monkey, cyclical gonadotropin secretion still occurs.
What is nondisjunction? When is it most likely to occur?
Nondisjunction is when a pair of chromosomes fail to separate during a meiotic division. This typically occurs in meiosis I, but can occur in meisois II.
What chromosomal patterns underlie Turner syndrome? Klinefelter syndrome? “Superfemales”? And one more that is lethal in utero?
Turner: XO; Klinefelter: XXY; “Superfemales”: XXX; YO combination is lethal in utero.
How are chromosomal abnormalities diagnosed?
Amniocentesis: sample of amniotic fluid collected by inserting a needle through the abdominal wall.
Chorionic villus sampling: fetal cells collected by a needle biopsy.
How does female pseudohermaphroditism occur? What external genitalia are present? What gonadal sex is present?
Exposure of a genetic female to androgens during week 8-13 of development. External male genitalia if exposed early, clitoral hypertrophy if exposed after the 13th week; gonadal sex is female.
What is a pseudohermaphrodite?
An individual with the genetic constitution and gonads of one sex and the genitalia of the other.
