Content Summary:
This chapter discusses the male and female reproductive anatomy and physiology, fertilization, pregnancy and parturition. Sperm and ova are called germ cells (gametes) and are formed in the gonads (testes and ovaries). Meiosis occurs, which is reduction division so each gamete contains only 23 chromosomes, which becomes 46 when the sperm fertilizes the ova. The normal number of chromosomes in humans is 46 or 23 pairs. Meiosis allows for 23 pairs of homologous chromosomes. The first 22 are autosomal chromosomes and the 23rd pair determines the sex of the baby.

Summary #1
Disorders can occur during embryonic sexual development. Hermaphroditism occurs when both ovarian and testicular tissue are present in the body. Approximately 34% of hermaphrodites have a tesis on one side and an ovary on the other. Approximately 20% of hermaphrodites have ovotestes (part testis and part ovary) on both sides. Approximately 46% have an ovotestis on one side and an ovary or testis on the other. This is a rare condition and may be caused by some embrionic cells receiving the short arm of the Y chromosome. A pseudo-hermaphrodite is a person with either testes or ovaries, not both, who have accessory sex organs and external genitalia that are incompletely developed or are inappropriate for their chromosomal sex. The most common cause of female pseudo-hermaphroditism is congenital adrenal hyperplasia. They would have mullerian duct derivatives but would also have wolffian duct derivatives and partially masculinized external genitalia. The most common cause for male pseudo-hermaphroditism is testicular feminization syndrome. They have normally functioning testes but lack receptors for testosterone.

Summary #2
Males can remain fertile into their 70's. Each ejaculation of semen has a volume of 1.5 to 5.0 ml. 45% to 80% of this fluid is produced by the seminal vesicles and 15% to 30% comes from the prostrate. There are approximately 60 to 150 million sperm per ml of seminal fluid. Oligospermia is a sperm concentration below 20 million per ml and suggests decreased fertility. Clinically, a sperm count below 50 million per ejaculation is considered significant. Oligospermia may be caused by heat from a hot tub or sauna, drug use, hormone imbalances, duct blockage or a low fructose concentration in the semen. A vasectomy is a surgical procedure that interferes with sperm transport and can be used as a contraception device.

Summary #3
Menopause occurs in most women around the age of 50. Menopause means the pause in the menses, so ovarian activity and menstruation cease. The ovaries become depleted of follicles and stop secreting estradiol, due to the change in the ovaries, and inhibin. FSH and LH secretion by the pituitary becomes elevated because of a lack of negative feedback from extradiol and inhibin. Estrone, formed by the messenchymal cells in the adipose tissue is the only estrogen found in the postmenopausal women. Women who have more adipose tissue have higher levels of estrogen and have less of a chance of developing osteoporosis. Withdrawal of extradiol secretion causes many of the symptoms menopausal women have. Vasomotor disturbances produce hot flashes. Urogenital atrophy causes loss of lubrication in the vagina. A side effect of menopause is an increased risk of atherosclerotic cardiovascular disease and an increased progression of osteoporosis.

Application:
For me as an OTA, I probably will not need to advise my patients on reproductive topics, but I will need to be aware of sexual function as this is one of the ADL that a patient may need help with. The more I understand what my patient may be dealing with, the better practitioner I will be.

Personally, I found the menopause section helpful. Many friends and family members are in this period of their life. I may be there, or at least pre-menopausal. I know that the text states that women with higher adipose tissue have less propensity to osteoporosis, but I would hope that diet and exercise would also be a contributing factor to keeping this disease at bay. I also have friends dealing with not being able to become pregnant, so that section of this chapter was interesting also.

Essential Question:
The ovarian and menstrual cycle:
  1. The hypothalamus secretes GnRH which stimulates the anterior pituitary to release FSH and LH
  2. FSH stimulates a few primary follicles to enlarge and one dominant follicle matures. FSH with LH promotes follicle cells to secrete estrogen.
  3. Estrogen stimulates the uterine lining to thicken and with the aid of inhibin, starts a negative feedback inhibition of FSH secretion. This prevents development of any additional follicles.
  4. Estrogen concentration rises and peaks on the 12th day. The dominant follicle enlarges.
  5. The anterior pituitary increases LH and FSH production that peaks on the 13th day.
  6. The primary oocyte undergoes the first meiotic division and forms the second oocyte. LH causes ovulation on the 14th day.
  7. LH changes the ruptured follicle into a corpus luteum and causes it to secrete increasing amounts of progesterone and smaller amounts of estrogen during the 15th to 25th days. Estrogen helps the uterine lining to thicken. Progesterone prepares the uterine lining to receive the embryo by promoting formation of blood vessels and glands. Progesterone, estrogen and inhibin cause a negative feedback on GnRH secretion which inhibits the release of FSH and LH.
  8. The corpus luteum degenerates if fertilization does not occur. Estrogen and progesterone secretion fall sharply from the 25th to 28th day.
  9. The cycle will begin again as lowered levels of estrogen and progesterone cause the uterine lining to breakdown and menstruation starts on the 1st day of the menstrual cyle. Estrogen and progesterone are not inhibiting the hypothalamus, so secretion of GnRH begins and the release of FSH and LH are stimulated and the ovarian cycle begins again.


References: Human Physiology by Stuart Ira Fox, Anatomy and Physiology by Stanley E Gunstream