1.6 Reproduction Flashcards
Are sperm and oocytes haploid or diploid?
Haploid
What are haploid gamete cells derived from?
Primordial germ cells
When are PGC’s set aside?
(Primordial germ cells)
3 weeks post fertilization
-Migrate from yolk sac to genital ridge
What does the protein encoded by SRY gene do?
Signals the cells around the germ cells to begin producing the steroid hormone testosterone
What does testosterone do in reproductive development?
Tells the boy’s gonad to develop into a testicle, and tells cells elsewhere in the body to begin growing a penis and male brain
How does female reproductive development occur?
Lack of testosterone leads to female development by default: ovaries, uterus, vagina
When are individuals with XY externally female?
When there is a mutated testosterone receptor
What triggers puberty?
The hypothalamus pumps out GnRH
What are the two goals of male reproduction?
Producing mature gametes and delivering the gametes
What is involved with delivering the gametes?
Erection, emission, ejaculation
Controlled by the autonomic nervous system
Reproductive hormone regulation
GnRH from hypothalamus
FSH and LH from anterior pituitary
Inhibin and testosterone
What does inhibin do?
Inhibits FSH release
Peptide hormone
What does testosterone do?
- Supports sperm formation
-Secondary sexual characteristics
(Also inhibits GnRH, FSH and LH)
What 3 hormones are required for spermatogenesis?
FSH, LH and testosterone
Pulsatile GnRH release from hypothalamus does what?
Stimulates FSH and LH release from pituitary
What is the difference in GnRH release in men and women?
Women have surges of GnRH and changes on a monthly basis, men do not
What does constant (non-pulsatile) GnRH infusion do?
Shuts down LH secretion from gonadotropes
What do leydig cells do?
Interstitial, steroidgenic cells produce testosterone in response to LH stimulation
Sertoli Cells
Sustentacular cells
- Support spermatogenesis in response to FSH & testosterone stimulation
- Produce inhibin
- Produce some estrogen
Spermatogonia
Diploid, 46 chromosomes
Bona fide stem cells (multipotent) undergoing mitosis and self renewal
One daughter cell enter meiosis to reduce chromosome # to 23
Sperm-motile cell
Bears either X or Y chromosome, must mature in epididymis
Where is sperm stored?
Epididymis
What is the vas deferens?
Smooth muscle surrounding ducts
Secondary effects of testosterone
- Maintains muscle mass and bone density
- Maintains remainder of “male plumbing”
- Kills off verbal communication neurons-increased aggression behaviors
Goals of Female Reproductive System
- Nurturing & Releasing gametes - eggs (oocytes)
2. Supporting the potential embryo (fetus)
What is a follicle?
Oocyte (gamete) surrounded by support cells
Follicle stages
Primordial Primary Secondary Tertiary (Vesicular or Graafian) -->Estrogen
Following ovulation, the follicle becomes..
Corpus luteum–> Progesterone & Estrogen
Theca cells
Respond to LH, produce androgen precursors to estrogen, become small luteal cells in corpus luteum
-Female equivalent of leydig cells
Granulosa cells
Respond to FSH, express aromatase enzyme to convert androgens to estrogens; become large luteal cells in corpus luteum
Oocytes: meiosis
Stuck in meiosis I for majority of woman’s life, paracrine communication with granulosa; estrogen–> GnRH–> LH surge restarts meiosis
Hormonal control in females
GnRH–> LH, FSH–>Estradiol (E2), Progesterone (P4), Inhibin
Two phases of the female cycle
Ovarian and Uterine (menstrual)
What is the dividing point of the two female cycles?
Ovulation
Human Chorionic Gonadotropin
Made by the fetal placenta, “rescues” the corpus lute from destruction during luteolysis
Follicular Stage of Ovarian cycle
- FSH surge stimulates new follicular wave
- Follicle selection
- LH and FSH stimulate higher and higher levels of estrogen
