female hormones

Question 1

What is oogenesis and the pathway for oocyte development

Answer 1

Oogenesis is the process of produing oocytes in the gonads (ovarys)
All oocytes development is initiated before birth -
- many selected and 1 dominent per cycle
Process before birth: all mitosis
- oogonia undergoes mitosis -> oogonia + primary oocyte
- primary oocyte initiates meiosis 1, halts prophase 1

Each cycle post menarche:
- handful of 1 oocytes selected - dominent follicle completes meiosis 1 -> secondary oocyte
- secondary oocyte -> initiates meiosis 2, halts metaphase 2
- ovulated 2nd oocyte + corona radiata
- if firtilised with sperm will complete metaphase 2 - otherwise atrisa

At each meiotic division a polar body is also made - undergoes atrisa

Question 2

What is the pathway of a follicle development and the cell types found in follicles

Answer 2

primordial follicle, around all 1 oocytes -> developes to primary follicle -> dominent follicle, secondary follicle -> vesicular follicle -> ovulation occurs releasing oocyte + corona radiata -> corpus luteum -> corpus albicans

Follicle made from
Granulosum cells - produce estradiol + form corona radiata
theca cells

Question 3

What are the main female horomones, secreted from and fuctions

Answer 3

Hypothalomus: Gonadotropin releasing hormone
- causes the release of FSH and LH

Anterior pituitary gland: FSH + LH
- FSH: stimulates follicular growth
- LH: stimulates ovulation + corpus luteum formation

Follicle: estradiol
- Causes complex AP feedback, LH post in high conc, FSH neg in low conc
- Stimulates endometrial, muscular, bone growth; 2nd sex characteristics

luteum: Inhibin + progesterone
- Inhibin: FSH negative feedback
- progesterone: GnRH negative feedback, endometrial maturation + maintaining pregnacy

Question 4

Describe what the ovarian cycle is

Answer 4

Occurs every 28 days - 2 phases

follicular phase - day 1-14
1. Follicles secrete low estrardiol -> negative feedback to FSH -> atresia of non-dominent follicles
2. Dominent follicle developes secreting high estradiol -> postive feedback to AP increase LH -> causes follicular rupture + ovulation
- oocyte + corona radiata to peritoneal space -> collected by uterine tube

luteal phase - day 15-28
1. corpus luteum formed (stimulated LH) -> secretes progesterone, inhibin & estradiol -> cause negative feedback to GnRH reduce FSH LH
2. If unfertilised - luteolysis -> corpus albicans, reduces progesterone secretion removes GnRH NF-> enables cycle to repeate

Question 5

Describe what the endometrial cycle

Answer 5

occurs at the same time as the ovarian cycle - 28 days
3 phases:

menstration - day 1-7, decreased progesterone causes endometrial degeneration and shedding -> bleeding
proliferation - day 8-14, estradiol promotes endometrial growth, glands, blood, tissue
secretion - day 14-28, progesterone promotes endometrial maturation - glands and sprial arterys

• if unfetilised, progesterone drops cycle repetes

Question 6

What is menarche and menopase how does this relate to the menstral cycle

Answer 6

Mentral cycle is a 28 day cycle occuring from menarche to menopause

Menarche is the first cycle - around age 12-13, caused due to increase estradiol during puberty by gonads

Menopause is the cessation of the menstral cycle - around age 50 due to lack of follicles - causes reduction in progesterone and estradiol secretion removes anterior pituitary negative feedback