1. Female reproductive hormones

2. Gross anatomy of female reproductive organs

3. Ovarian hormone production
Cyclic changes
Cyclic changes in ovarian structure
Ovaries
Characterized as an organ of constant change
A series of dynamic changes in a very predictable manner during the reproductive cycle.
Cyclic changes in uterine structure

4. Cyclic changes
Development of large fluid-filled structures called follicles
Rupture of the ovulatory follicle and release of the oocyte (ovulation)
Formation of a corpus luteum from remnants of the ovulated follicle.

5. Destruction of the corpus luteum (CL)
Prostaglandin F2alpha (PGF2a) near the end of the cycle if pregnancy is not initiated
Demise of the CL
Development of an ovulatory follicle and release of the oocyte at ovulation
Series of events takes place in the predictable manner
Once every three weeks in cows
Once every four weeks in humans

6. Follicular
Phase
Luteal
Phase

7. Pattern of follicular development and changes in blood hormone concentrations
Ovulation
Ovulation
Ovulation CH CL C
Adapted from
Lucy et al., 1992
The pattern of follicular development in human and cattle resembles that of a wave (follicular wave)
One cohort of follicles emerges in the beginning
One of the follicles within the cohort becomes the dominant follicle and continues to grow
After reaching its growth plateau, the dominant follicle begins to shrink, and a new cohort emerges shortly thereafter

8. Pattern of follicle development in cattle and humansLH LH
Ovulation
Ovulation + + + + + + E E E E E E
FSH E E E E
Adopted from
Ginther et al., 1996
Ireland et al., 2000
FSH=follicle stimulating hormone
LH=luteinizing hormone

9. Structure of ovarian follicle
Granulosa cells
Basement
membrane
Antrum
Oocyte
Theca externa
Theca interna

10. Synthesis of estrogens
Theca cells
Androgen production
Granulosa cells
Estradiol production
Progesterone production by both theca and granulosa cells

11. Structure of ovarian follicle
Granulosa cells
Basement
membrane
Antrum
Oocyte
Theca externa
Theca interna

12. Two-cell, two-gonadotropin theory
Ovarian steroidogenesis
LH acts on theca cells to produce androgens
FSH acts on granulosa cells to produce estradiol using thecal androgens
FSH
Essential for normal granulosa cell development and function
Expression of LH receptors in large follicle

13. Theca cells
cAMP
FSH LH
Granulosa cells

14. Pattern of follicular development and changes in blood hormone concentrations+ LH
Ovulation
FSH

15. Role of estradiol Proliferation of endometrium
Transcription and translation
Thickening of stroma
Mitosis
Stimulated by growth factors from stroma
Growth and differentiation
Increased metabolic activity
Expression of progesterone receptors

16. Effects of progesterone
Differentiation of endometrium
Inhibition of estradiol-induced proliferation
Mediated by stroma
Secretion
Proteins
Critical for implantation

17. Uterine endometrium Mucosal lining of the uterus Inner-most lining
Well-developed in human compared to other species
Placentation
Menstruation (shedding of endomertial tissue)
Spiral arteries
Hemorrhage (changes in blood flow)
Renewal of endometrium during each reproductive cycle

18. Hormone-induced changes in endometrium
Cyclic in nature
Re-epithelialization
Menstrual-postmenstrual transition
Endometrial proliferation
Estradiol
Epithelial secretion
Estradiol and progesterone
Premestrual ischemia
Loss of blood supply to epithelia
Menstruation

19. Role of estradiol Proliferation of endometrium
Transcription and translation
Thickening of stroma
Mitosis
Stimulated by growth factors from stroma
Growth and differentiation
Increased metabolic activity
Expression of progesterone receptors

20. Luteal structures After ovulation
The oocyte is released from the preovulatory follicle
Theca and granulosa cells remaining in the follicular wall undergo dramatic changes
Formation of a corpus luteum.
A shift from producing estradiol (granulosa) and androgen (theca) to producing large amounts of progesterone

21. Luteal structures Three structures
Corpus hemorrhagicum (CH)
Corpus Luteum (CL)
Corpus Albicans (CA)
These names refer to the same structure (luteal) but with differing features characteristic of different stages of the reproductive cycle

22. Luteal structures CH CH Early CH Developing CH
The corpus hemorrhagicum (bloody body)
During the early part of the luteal phase of the reproductive cycle
Appears red
Small blood vessels within the follicle rupture during ovulation
Collapse of follicular wall into many folds after leakage of follicular fluid into many folds CH CH
Early CH
Developing CH

23. Luteal structures The corpus luteum (yellow body) CL CL with cavity CL
Found during the middle part of the luteal phase of the reproductive cycle
The major source of progesterone
Some have a CL with a very large fluid-filled cavity, whereas others have a CL without a distinguishable cavity CL
CL with
cavity CL
CL without
cavity

24. Luteal structures The corpus albicans (white body)
A white, fibrous tissue
Remains of the CL
Loss of ability to produce progesterone
Death of cells in the CL
It eventually completely loses the ability to produce progesterone
Leads to follicular phase CA CA
Early CA
Advanced CA

25. Effects of progesterone
Differentiation of endometrium
Inhibition of estradiol-induced proliferation
Mediated by stroma
Secretion
Proteins
Critical for implantation

26. Regulation of luteal function
Luteal cells
Small (around 25 % of total cells in the CL)
Very small contribution to basal production of progesterone
Responds to LH and produce progesterone (5 to 20 X above the basal level)
Large (around 10 % of total cells in the CL)
Very high
No significant response to LH

27. Hormonal factors LH Estradiol Prolactin
Extremely crucial during development
May not be necessary during the middle of luteal phase
Estradiol
Only in some species (i.e. rabbits)
Prolactin
During early stage of pregnancy in rats and mice

28. Action of progesterone
Increase in cytoplasm of stroma
Psuedodiciduation

30. Effects on other uterine tissues
Myometrium (smooth muscle)
Excitability and contraction
Depressed by progesterone
Increased by estradiol

31. Menstruation Absence of pregnancy Initiation of endometrium remodeling
Alteration of extracellular matrix
Leukocyte infiltration
Death and removal of tissue
Regeneration of tissue

32. Menstruation Withdraw of steroid hormones
Constriction of arterioles and coiled arteries
Ischemia
Precedes bleeding
Bleeding
Relaxation of arteries
Induction of hypoxia-reperfusion injury (formation of hematoma)
Detachment of tissue fragments

33. Effects of steroid hormones on female reproductive tract
Oviduct
Secretion of oviductal fluid
Nutrients for the oocytes
Sperm survival and capacitation
Early embryonic development
Cervix
Estradiol
Relaxation of muscle
Secretion of watery mucus
Progesterone
Tightening of muscle
Secretion of thick mucus