1. Reproductive System-L3
Faisal I. Mohammed, MD, PhD
University of Jordan

2. The Female Reproductive Cycle
Encompasses ovarian and uterine cycle, hormonal changes that regulate them, and related changes in breast and cervix
Ovarian cycle – series of events in ovaries that occur during and after maturation of oocyte
Uterine (menstrual) cycle – concurrent series of changes in uterine endometrium preparing it for arrival of fertilized ovum
University of Jordan

3. Hormonal regulation Gonadotropin-releasing hormone (GnRH)
Secreted by hypothalamus controls ovarian and uterine cycle
Stimulates release of follicle-stimulating hormone (FSH) and luteinizing hormone (LH) from anterior pituitary
FSH
Initiate follicular growth
Stimulate ovarian follicles to secrete estrogens
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4. Hormonal regulation…contLH
Stimulates further development of ovarian follicles
Stimulate ovarian follicles to secrete estrogens
Stimulates thecal cells of developing follicle to produce androgens to be converted into estrogens
Triggers ovulation
Promotes formation of corpus luteum – produces estrogens, progesterone, relaxin and inhibin
University of Jordan

5. Hormonal regulation Estrogens secreted by ovarian follicles
Promote development and maintenance of female reproductive structures and secondary sex characteristics
Increases protein anabolism including building strong bones
Lowers blood cholesterol
Inhibit release of GnRH, LH and FSH
Progesterone
Secreted mainly by corpus luteum
Works with estrogens to prepare and maintin endometrium for implantation and mammary glands for milk production
Inhibits secretion of GnRH and LH
University of Jordan

6. Hormonal regulation Relaxin Produced by corpus luteum
Relaxes uterus by inhibiting contraction of myometrium
At end of pregnancy, increases flexibility of pubic symphysis and dilates uterine cervix
Inhibin
Secreted by granulosa cells of growing follicles and by corpus luteum
Inhibits secretion of FSH and LH
University of Jordan

7. Secretion and physiological effects of hormones in the
female reproductive cycle
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8. 4 Phases Typical duration 21-35 days Assume a duration of 28 days
Menstrual phase
Preovulatory phase
Ovulation
Postovulatory phase
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9. The female
reproductive
cycle
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10. Menstrual phase or menstruation
Roughly first 5 days of cycle
First day of menstruation is day 1 of new cycle
Events in ovaries
Under FSH influence, several primordial follicles develop into primary follicles ad then into secondary follicles
Takes several months
Follicle that begins to develop in one cycle may not mature for several cycles later
University of Jordan

11. Menstrual phase or menstruation…cont
Events in uterus
Menstrual discharge occurs because declining levels of estrogens and progesterone stimulate release of prostaglandins causing uterine spiral arterioles to constrict
Cells deprived of oxygen begin to die
Only stratum basilis remains
University of Jordan

12. Preovulatory phase More variable in length
Lasts from days 6-13 in a 28 day cycle
Events in ovaries
Some of secondary follicles begin to secrete estrogens and inhibin
Dominant follicle – one follicle outgrown all others
Estrogens and inhibin of dominant follicle decrease FSH causing other follicles to stop growing
Fraternal (nonidentical) twins result when 2 or 3 secondary follicles become codominant and are ovulated and fertilized at the same time
University of Jordan

13. Preovulatory phase
Normally, one dominant follicle becomes the mature (graffian) follicle
In ovarian cycle, menstrual and preovulatory phases are termed follicular phase because follicles are growing
Events in uterus
Estrogens stimulate repair of endometrium
Cells of stratum basalis undergo mitosis to form new stratum functionalis
Thickness of endometrium doubles
In uterine cycle, preovulatory phase is the proliferative phase because endometrium is proliferating
University of Jordan

14. Ovulation
Rupture of mature (graffian) follicle and release of secondary oocyte
Day 14 of 28 day cycle
High levels of estrogens exert a positive feedback effect on cells secreting LH and GnRH
Fertilization can occur after ovulation
Sperms can live hours inside the femal reproductive tract
Ovum can be fertilized within 48 hours after ovulation
The best time for fertilization and conception (pregnancy) is to have sexual intercourse hours before ovulation to 48 hours after ovulation
Period before that time and after that time is called the safe period and it is the principle for physiological contraception method
University of Jordan

15. Ovulation High levels of estrogens from almost mature
follicle stimulate
release of more
GnRH and LH
LH surge
brings about
ovulation
Ovulated
secondary
oocyte
Hypothalamus
Anterior pituitary
GnRH promotes
release of FSH
and more LH
Ovary
Corpus hemorrhagicum
(ruptured follicle)
Almost mature
(graafian) follicle LH
GnRH 1 2 3
High levels of
estrogens from
almost mature
follicle stimulate
release of more
GnRH and LH
Hypothalamus
Anterior pituitary
GnRH promotes
release of FSH
and more LH
Ovary
Corpus hemorrhagicum
(ruptured follicle)
Almost mature
(graafian) follicle LH
GnRH 1 2
High levels of
estrogens from
almost mature
follicle stimulate
release of more
GnRH and LH
Hypothalamus
Anterior pituitary
Ovary
Corpus hemorrhagicum
(ruptured follicle)
Almost mature
(graafian) follicle LH
GnRH 1
Ovulation
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16. Postovulatory phase Duration most constant of phases
Lasts for 14 days in 28 day cycle (day 15-28)
Events in one ovary
After ovulation, mature follicle collapses to form corpus luteum under the influence of LH
Secretes progesterone, estrogen, relaxin and inhibin
In the ovarian cycle, this is the luteal phase
University of Jordan

17. Corpus luteum If oocyte not fertilized, corpus luteum lasts 2 weeks
Degenerates in corpus albicans
As levels of progesterone, estrogens and inhibin decrease, release of GnRH, FSH, and LH rise sue to loss of negative feedback
Follicular growth resume as new ovarian cycle begins
If oocyte is fertilized, corpus luteum lasts more than 2 weeks
Human chorionic gonadotropin (hCG) produced by chorion of embryo about 8 days after fertilization stimulates corpus luteum
University of Jordan

18. Events in uterus
Progesterone and estrogens produced by corpus luteum promote growth of endometrium
Because of secretory activity of endometrial glands, this is the secretory phase of uterine cycle
Changes peak about 1 week after ovulation when a fertilized ovum might arrive in uterus
If fertilization does not occur, levels of progesterone and estrogens decline due to degeneration of corpus luteum
Withdrawal of estrogens and progesterone causes menstruation
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19. Hormonal interactions in the ovarian and uterine cycles
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20. Breast / Mammary glands
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21. Breast / Mammary glands
Nipple has openings of lactiferous ducts
Areola – pigmented area
Mammary gland – modified sudoriferous gland that produces milk
15-20 lobes divided into lobules composed of alveoli (milk-secreting glands)
Estrogen promotes the development of the ductal system of the breast
Progesterone promotes the development of the alveolar system –milk secretory system-
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22. University of Jordan

23. Thank You
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