Reproduction Flashcards
1
Q
What is the role of the SRY gene?
A
Triggers the embryonic gonads developing into testes
2
Q
What are three roles of testosterone?
A
- prenatal development of male genitalia
- sperm production
- development of male secondary sexual characteristics
3
Q
What is the role of estrogen and progesterone in sex determination?
A
- Cause the development of female reproductive organs in the absence of testosterone
- cause the development of female secondary sexual characteristics during puberty
4
Q
What is the role of the sperm duct? Seminal vesicle and prostate gland? Urethra? Epididymis? Testes?
A
- Sperm duct transfers sperm during ejaculation.
- Seminal vesicle and prostate gland secrete fluids containing alkali, proteins, and fructose that are added to sperm to make semen.
- Urethra transfers semen during ejaculation and urine during urination
- Epididymis stores sperm until ejaculation
- Testes produce sperm
5
Q
What is the role of the oviduct? Ovary? Endometrium? Cervix? Vagina?
A
- Oviduct collects eggs at ovulation, provide site for fertilization and then move the embryo to the uterus
- Ovary produces eggs, estrogen, and progesterone
- Endometrium lines the uterus and makes it safe for reproduction
- Cervix protects fetus during pregnancy and then dilates to provide birth canal
- Vagina stimulates penis to cause ejaculation and provides a birth canal
6
Q
Describe the follicular phase.
A
- Group of follicles develop in the ovary due to FSH
- An egg stimulated to grow in each follicle, releasing estrogen as they develop
- Lining of the uterus is repaired and starts to thicken by estrogen
7
Q
Describe the luteal phase.
A
- Wall of follicle that released egg becomes the corpus luteum due to LH causing influx of cells
- Continued development of endometrium prepares it for implantation due to progesterone release by corpus luteum
- If fertilization does not occur, corpus luteum breaks down, resulting in decreased levels of estrogen and progesterone.
- Lowered progesterone levels result in uterine lining breaking down. Leads to lining, egg, and some blood leaving the vagina during menstruation.
- As estrogen levels drop, inhibition of FSH by estrogen wears out and o the pituitary gland produces FSH and the cycle starts again.
8
Q
Role of FSH? LH? Estrogen? Progesterone?
A
- FSH stimulates development of follicles and secretion of estrogen by follicle wall
- LH stimulates completion of meiosis in the oocyte, partial digestion of follicle wall so that it can burst at ovulation. Promotes development of the corpus luteum.
- Estrogen stimulates repair and thickening of endometrium and an increase in FSH receptors (positive feedback). At high levels, inhibits FSH secretion, stimulates LH production.
9
Q
Describe ovulatory phase.
A
- Follicles reach full development.
- High levels of estrogen in the blood cause the pituitary gland to decrease FSH production by negative feedback and begin secretion of LH by positive feedback, causing decreased levels of estrogen.
- When LH levels reach some threshhold, the most developed follicle breaks open, releasing its egg into the oviduct. Other follicles degenerate.
10
Q
How does in-vitro fertilization occur?
A
- FSH and LH given in high doses to stimulate production of multiple ova
- 34-38 hours before collection, woman receives hormone injection to stimulate egg maturation.
- Eggs removed with a hollow needle
- Sperm sample collected from partner or donor and checked for viability
- Eggs mixed with sperm and cultured. Fertilized eggs are incubated.
- Embryos are transferred to the uterus and implanted.
- Screen for pregnancy.
11
Q
What is the germinal epithelium? Primary follicle? Maturing follicle? Secondary oocyte? Zona pellucida?
A
- Germinal epithelium is the outer layer of cells.
- Primary follicle is an immature ovarian follicle. Maturing follicle is one ready for ovulation.
- Secondary oocyte is a cell in an ovary that may undergo meiotic division to form an ovum in Meioisis II.
- Zona pellucida is a layer of gel composed of glycoproteins.
12
Q
What are interstitial cells? Germinal epithelium cells? Sertoli cells? Developing spermatazoa?
A
- Interstitial cells produce testosterone.
- Germinal epithelium cells are the outer layer of cells where sperm production begins.
- Sertoli cells are elongated cells which produce an environment and nutrients which are conducive to spermatogenesis.
- Developing spermatozoa are developing sperm cells
13
Q
What is the corona radiata? Zona pellucida?
A
- Corona radiata: layer of follicle cells outside of egg
- Zona pellucida: layer of glycoprotein ‘gel’ around egg
14
Q
Outline spermatogenesis.
A
- Spermatagonia (2n) grow into larger cells called primary spermatocytes (2n)
- Primary spermatocytes (2n) carry out the first stage of meiosis, producing 2 secondary spermatocytes (n).
- Secondary spermatocytes carry out Meioisis II, producing four spermatids (n).
- Spermatids become associated with sertoli cells, which help the spermatids develop into spermatozoa (n).
- Mature sperm (spermatozoa) detach from sertoli cells and are eventually carried out of the testes by the fluid in the center of the seminiferous tubule.
15
Q
Outline oogenesis.
A
- Oogonia cells (2n) in the ovary divide by mitosis to make more oogonic cells. Oogonia grow into larger cells called primary oocytes (2n).
- Primary oocytes undergo meiosis I. Primary oocytes and a single layer of follicle cells form a primary follicle. Primary oocyte completes meiosis I, forming two saughter nuclei (n). Cytoplasm of primary oocyte develops unequally, forming a secondary oocyte and a small polar body.
- Secondary oocyte starts meiosis II but stops at prophase II. Follicle cells, meanwhile, are reproducing quickly and follicle fluid is forming.
- Mature follicle bursts at the time of ovulation. The released egg is still a secondary oocyte (n).
