Female reproductive Flashcards
What are the two main functions of the ovary?
Produce haploid gametes capable of being fertilized
Produce sex hormones: oestrogen progesterone, and peptides (e.g. inhibin, activin) which act both systemically and locally.
When does meiosis of gametes occur in females?
Starts and arrests in foetal life
After birth what slowly happens to the follicles?
Atresia (apoptosis)
How many primary oocytes are produced?
6-7million
How many oocytes does a woman ovulate in her lifetime?
~400
What does a follicle consist of?
Primary oocyte, surrounded by its zona pellucida, granulosa cells and later, thecal cells
What substance surrounds the primary oocyte?
Zona pellucida - glycoprotein
What does interstitial tissue of ovary contain?
Corpora lutea and corpora albicantia from previously ovulated follicles/ matter from atretic follicles
Connective tissue, vessels and nerves.
What junctions link granulosa cells?
Gap junctions
How many layers of the thecal cells surround a follicle?
2, inner theca interna and outer theca externa
What is the role of the theca interna cells?
Secrete androgens
What is the role of the theca externa?
Protective capsule
After the primary oocyte leaves the follicle in ovulation, what forms the corpus luteum?
Granulosa and theca interna cells
When is day 1 of the menstrual cycle?
The first day of menstruation
How many days does the menstrual cycle last?
~28 days
What determines length of the menstrual cycle?
Follicle growth and corpus luteum lifespan
What are the two phases of the menstrual cycle and why are they named as such?
During the first half the reproductive system is dominated by a developing follicle (follicular phase)
After ovulation products of the corpus luteum dominate (luteal phase).
What triggers puberty?
Activation of kisspeptin neurones
What does kisspeptin activation stimulate?
Release of hypothalamic GnRH
What does GnRH stimulate?
Release of FSH and LH from the anterior pituitary
When to primordial follicles appear?
16-24 weeks gestation
What are the layers of the primordial follicle?
Primary oocyte surrounded by a single layer of flat pregranulosa cells
What happens in the initial stage of follicle development?
Primary oocyte enlarges and the granulosa cells become rounded to produce a primary follicle
What does a primordial follicle develop into?
Primary follicle
How does a primary follicle change into a secondary follicle
Mitosis in the single layer of granulosa cells and differentiation of surrounding stromal cells to form thecal cells produces a secondary follicle.
Granulosa cells have FSH receptors and the thecal cells LH receptors.
What happens when secondary follicles are stimulated by FSH
Secrete fluid which coalesces to form an antrum and the follicle is called an early antral (tertiary) follicle.
Which follicular cells bind to FSH and which to LH
Granulosa cells have FSH receptors and the thecal cells LH receptors.
What is a Graafian follicle?
Mature tertiary/antral follicle
Which granulosa cells are shed with the oocyte at ovulation?
Cumulus granulosa cells
What happens when primary oocyte undergoes meiosis I?
2n primary oocyte splits into secondary (n) oocyte and polar body (n)
What does FSH cause granulosa cells to do?
Stimulates their division
Stimulates the secretion of antral fluid
Activating them to convert the androgens provided by the thecal cells to oestrogen by stimulating production of aromatase
Stimulates production of peptide hormones and growth factors
Stimulates the production of LH receptors in selected follicles.
What does LH cause thecal cells to do?
Causes them to grow and divide
Secrete androgens