CMB1004/L29 Reproductive System Flashcards
What hormones are released by the testes?
Androgens (and oestrogens)
What hormones do ovaries secrete?
Oestrogens (and androgens)
Progesterone
Name the 2 types of gametogenesis.
Spermatogenesis
Oogenesis
Where do oocytes arrest?
Prophase of meiosis division 1 within primordial follicles
How many eggs are released by ovulation in a female’s lifetime?
500
Give the 3 phases of the ovarian cycle.
Phase 1 - follicular phase
Phase 2 - ovulation
Phase 3 - Luteal phase
How long does phase 1 of the ovarian cycle last?
Several months
Describe the pre-antral phase (in phase 1/follicular phase of ovarian cycle). (2)
Change of primordial follicle to primary follicle (zona pellucida formation)
Primary follicle matures into mature pre-antral follicle with thecal cell layer
What hormone limits the number of primary follicles developing at one time?
Antimullerian hormone
Describe the antral phase (in phase 1/follicular phase) of the ovarian cycle. (4)
Appearance of fluid filled atria
Increased layers of zona granulosa
Thicker zona pellucida
Theca interna more apparent
What is the growth of follicles dependent on?
Pituitary FSH
What is the role of theca cells?
Catalysis of androgen from cholestrol
What is the role of granulosa cells?
Contain aromatase to convert androgen to oestrogen
Describe the pre-ovulatory phase (in phase 1/follicular phase) of the ovarian cycle. (4)
Surge in LH causes arrest in metaphase of meiosis II
Haploid secondary oocyte and polar body forms
LH receptor and enzyme expression - progesterone production
Cytokines and hydrolytic enzymes released
What kind of event is ovulation?
Inflammatory
What is released into the peritoneal cavity during ovulation?
Oocyte, zona pellucida and corona radiata
Which structure is crucial for the capture of the oocyte by the fimbrae during ovulation?
Corona radiata
Where do the remnants of the follicle in the ovary go on to?
Corpus luteum
What is the major product of the luteal phase?
Progesterone
What occurs in the luteal phase of the ovarian cycle? (3)
Corpus luteum develops
Granulosa cells fill with lipid
Oestrogen initially decreases due to LH surge but rebounds
What occurs in the luteal phase if there is no pregnancy? (3)
Corpus luteum degenerates into corpus albicans
Oestrogen and progesterone falls
LH and FSH rise
What occurs in the luteal phase if there is a pregnancy? (2)
Placenta released human chorionic gonadotrophin
Corpus luteum persists
In the two cell model of ovarian steroidogenesis, what is the hormone product of theca cells?
Androstenedione
What is the role of Gonadotropin releasing hormone (GnRH)? (3)
Pulsatile release
High frequency promotes LH
Low frequency promotes FSH
What is the role of follicle stimulating hormone? (4)
Stimulates recuitment and growth of immature follicles
Upregulates CYP19 (aromatase)
Induces expression of LH receptors in granulosa cells
Prevents apoptosis/atresia of antral follicles
What is the role of luteinising hormone (LH)? (4)
Promotes androgen production in theca cells
Surges in last 1-2 days to trigger ovulation
Promotes progesterone production in granulosa cells
Maintain corpus luteum
What is the role of oestrogens?
Prepares reproductive tract for potential fertilisation and pregnancy
What is the role of progesterone?
Promotes uterine and uterine tube secretions to maintain and support potential implantation
What is the role of inhibin A and B? Where is it produced?
Represses FSH secretion
Secreted by granulosa cells
