Chap 46 - Animal reproduction Flashcards
Sertoli cells (testes)
Promote spermatogenesis & inhibits anterior pituitary gland when stimulated by FSH.
Leydig cells (testes)
Produce testosterone & promotes spermatogenesis in response to LH.
4 methods of asexual reproduction
- Budding
- Fission
- Fragmentation
- Parthenogenesis
Parthenogenesis
Asexual reproduction where an egg develops without fertilisation.
Ovarian vs uterine cycles
Ovarian - regulates maturation of oocytes/ovulation
Uterine - regulates endometrium & menstruation
Ovarian cycle summary
- Anterior pituitary releases some LH & FSH.
- Follicle grows & makes oestradiol, releasing more as it matures.
- High oestradiol stimulates GnRH production.
- This causes a peak in LH.
- Peak in LH leads to ovulation.
- Corpus luteum keeps making oestradiol, which inhibits LH & FSH to prevent next follicle growing until the corpus luteum withers.
Uterine cycle summary
- As follicle grows, increasing oestradiol promotes endometrium growth.
- Corpus luteum makes more oestradiol and progesterone, leading to more growth of endometrium, arteries, and endometrial glands.
- When hormone levels drop as corpus luteum withers, arteries constrict and menstruation yay.
Blastocyst
Little ball of cells with a hollow center 7 days after fertilisation. Implants onto uterine wall at this stage.
Length of human pregnancy
Averages 266 days (38 weeks)
First trimester
- Placenta develops at 4th week.
- Organogenesis.
- Embryo considered a fetus at the end.
Chorionic villi
Extensions of fetal tissue & blood vessels into placental blood pool - facilitates nutrient diffusion.
Placenta structure
Pool of maternal blood in the middle, with maternal tissue & blood vessels on one side and fetal tissue on the other. Chorionic villi extends into pool.
Progestin
Synthetic compound similar to progesterone.
Used for contraceptives - ‘pauses’ ovarian cycle.
Menopause
Ovaries don’t response anymore to LH or FSH. Oestradiol production decreases.
