Reproduction Flashcards
What is mitosis?
Germ cell proliferation.
Which type of cell division is mitosis? Which type of cell division is meiosis?
Haploid/diploid?
Mitosis = Diploid
Meiosis = Haploid
When does mitosis and meiosis occur in females and males sex cells, respectively?
In females, mitosis occurs in the fetus, whereas meiosis occurs in the reproductive adult.
In males, mitosis AND meiosis occur in the reproductive adult.
In females, when is Meiosis I under arrest?
Primary oocyte arrested in fetus until selected for ovulation.
In females, when is Meiosis II under arrest?
Secondary oocyte arrested in reproductive adult unless fertilized.
What happens if an egg is unfertilized?
It degenerates.
How many eggs does 1 primary oocyte yield?
1 egg.
How many sperm does 1 primary spermatocyte yield?
4 sperm.
What happens to polar bodies? At what points are they created?
They disintegrate.
First polar body created during Meiosis I. Second polar body created during Meiosis II.
What is the main hormone product of testes?
Testosterone (an androgen).
What is the main hormone product of ovaries?
Estradiol (an estrogen) and progesterone (a progestin).
What do all gonadal steroids mediate?
Feedback at hypothalamus and anterior pituitary, with the exception of estradiol.
What will sustained high levels of estradiol cause?
Massive surge release of LH/FSH.
Positive feedback.
Which androgen-dependent feature occurs in some species of male mammals?
Testicular migration into scrotal sac.
What is cryptochidism?
The failure of testicles to descent.
What temperature is required for normal spermatogenesis?
2-3 degrees less than body temperature.
What is the epididymis?
A highly convoluted duct behind the testis, along which sperm passes to the vas deferens.
What is a spermatid?
It has completed meiosis, but not yet undergone cell remodeling to become final sperm.
How is the “blood-testes barrier” formed?
A formation between he basal lamina, cells associated with basal lamina, and tight juctions between Sertoli cells.
What are the effects of testicular androgens?
- Negative feedback control of LH/FSH and GnRH.
- Primary sex characteristics
- Secondary sex characteristics
- Behaviour
What are the primary sex characteristics for males?
- Development and maintenance of internal and external genitalia.
- Support of spermatogenesis.
What is testosterone often converted into, once in the target tissues?
DHT.
What is DHT required for?
- Differentiation of external genitalia during development.
- Development and support of accessory sex glands.
- Male pattern baldness, acne, facial hair.
What is the endometrium?
The inner lining of the uterus.
What is the myometrium?
Smooth muscle of uterus.
What are the layers of a tertiary follicle (from outermost to innermost)?
- Theca
- Basal lamina
- Granulosa cells
- Antrum
Describe the levels of FSH and LH during the follicular phase, ovulation, and the luteal phase.
During the follicular phase, FSH and LH levels are both low.
FSH and LH levels rise dramatically in preparation for ovulation, and right after ovulation, immediately drop off. Higher levels of LH than FSH.
During the luteal phase, levels of FSH and LH return to baseline.
What is considered the beginning of the follicular phase?
Begins with the luteal regression -> Low ovarian steroids -> Menses.
What happens to the ovary during the follicular phase?
- Selected follicle begins to grow and secrete estrogen.
- Sustained exposure to high estrogen/low progesterone causes massive release of gonadotropins.
- LH surge leads to ovulation.
What happens to the uterus during the follicular phase?
- Part of the endometrial lining shed due to steroid withdrawal, leading to menses.
- Rising estrogen (from maturing follicle) stimulates regrowth of lining (proliferative phase).
What is considered the beginning of the luteal phase?
Begins with LH surge, which triggers ovulation.
What happens to the ovary during the luteal phase?
- Oocyte escapes ovary, completes meiosis I in response to LH surge, then arrests again in meiosis II.
- Somatic cells of ovulatory follicle transform into luteal cells, which form solid, progesterone-secreting structure (luteinization).
- High ovarian steroids suppress gonadotropins, preventing growth of large follicles.
- In the absence of pregnancy, luteal regression.
What happens to the uterus during the luteal phase?
- Under influence of progesterone and estrogen, continues to prepare for pregnancy (secretory phase).
- Luteal regression -> steroid withdrawal -> menses.
What is parturition?
- Cervical softening/ripening
- Initiation of rhythmic uterine contractions
- Delivery of the baby
- Expulsion of the placenta
What is parturition controlled by?
Sequential cascade of hormones.
What is the role that oxytocin plays with parturition?
Positive feedback/neuroendocrine reflex.
What is the process of labour and positive feedback?
1) Cervical stretch
2) Oxytocin release
3) Uterine contractions
4) Push baby against cervix
5) Causes more cervical stretch
6) Delivery of baby ends cycle
