Flashcards in 6.0 The Ovarian Cycle Deck (17)
How long is the ovarian cycle?
What is the name of the period of the ovarian cycle before ovulation? How long is it?
Follicular stage (10-14 days)
What is the name of the period of the ovarian cycle after ovulation? How long is it?
Luteal phase (12-15 days)
What hormone dominates pre-ovulation?
What hormone dominates post-ovulation?
What is the fate of preantral follices?
Majority undergo atresia
Some spontaneously form antral follicles
No antral follicles can form in luteal phase due to effect of progesterone
What are the effects of oestrogen in follicular stage?
1) ↑ LH → follicular growth and maturation to pre-ovulatory follicle
2) Arterial growth
3) Thickening of endometrium towards ovulation
4) ↑ mucus secretion
During what phase does the endometrium develop progesterone receptors?
Follicular phase (even though no progesterone in this phase)
What occurs in luteal phase?
1) Arteries taken on spiral form
2) ↑ Progesterone → ↓ mucus secretion and prevents sperm penetration
What is the property of mucus in follicular and luteal phase?
Follicular = Spinnbarkeit (towards ovulation)
Luteal = Ferning (uniform, organised structure)
What are the endocrine cells of the pituitary gland?
1) Gonadotrophs → LH + FSH
2) Somatotrophs → GH
3) Lactotrophs → Prolactin
4) Thryotrophs → TSH
5) Corticotrophs → ACTH
What nuclei are involved with GnRH release?
1) Medial pre-optic nucleus
2) Arcuate nucleus
What feedback loops exist in males?
Only negative feedback
Androgens → ↓ FSH + LH secretion by negatively inhibiting Hypothalamus and ant. pituitary
Inhibin → ↓ FSH secretion by negatively inhibiting the ant. pituitary ONLY
"What is the ""pelvic clock"""
A term used to describe the relationship of follicular dynamics and the timing of the menstrual cycle
What alterations are seen in LH secretion around puberty?
- Low LH secretion
- Nocturnal augmentation of LH secretion
- Establishment of high basal levels of LH secretion with no diurnal rhythm
What precedes LH, FSH and sex steroid increases in puberty?
Exogenous GnRH pulses → initiate puberty