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Female Reproductive Hormones
- Function of the Ovaries
- Production of female gametes (ova)
- Production of female sex hormones -
oestrogens and progesterone
- Production of female gametes (ova)
- The Ovarian Cycle
- Primordial follicles made up of an
oocyte surrounded by a single cell layer
- 400 000 present in each ovary at menarche (first period)
- After follicular selection the cells divide to form 2 layers
- outer stromal cells and inner granulosa cell layer
- A layer of theca cells (theca externa and theca interna) develops
between the 2 layers and oocyte is surrounded by zona pellucida
- Follicular antrum develops and fills with follicular fluid
- Mature oocyte is suspended in the follicular fluid
and attached to the granulosa layer by a stalk
- During ovulation the follicle ruptures and releases the oocyte
- The antrum fills with blood, forming a corpus haemmorrhagicum
- Develops into the corpus luteum
- Corpus luteum regression forms the corpus albicans
- Corpus luteum regression forms the corpus albicans
- Develops into the corpus luteum
- The antrum fills with blood, forming a corpus haemmorrhagicum
- During ovulation the follicle ruptures and releases the oocyte
- Mature oocyte is suspended in the follicular fluid
and attached to the granulosa layer by a stalk
- Follicular antrum develops and fills with follicular fluid
- A layer of theca cells (theca externa and theca interna) develops
between the 2 layers and oocyte is surrounded by zona pellucida
- 400 000 present in each ovary at menarche (first period)
- Oestrogens are the main secretory
product of the developing follicle
- Secreted by theca and granulosa cells
- Theca cells release testosterone which is
converted to oestradiol by granulosa cells
- Theca cells release testosterone which is
converted to oestradiol by granulosa cells
- Secreted by theca and granulosa cells
- Progesterone is the main secretory
product of the corpus luteum
- Primordial follicles made up of an
oocyte surrounded by a single cell layer
- Ovarian Steroidogenesis
- Cholesterol
- Pregnenolone
- Progesterone
- 17-alpha-hydroxyprogesterone
- Androstenedione
- Androstenedione
- 17-alpha-hydroxyprogesterone
- 17-alpha-hydroxypregnenolone
- DHEA
- Androstenedione
- Oestrone (via Aromatase)
- In
- In
- Testosterone
- 17-beta-oestradiol (via Aromatase)
- equilibrium
- equilibrium
- 17-beta-oestradiol (via Aromatase)
- Oestrone (via Aromatase)
- Androstenedione
- DHEA
- Progesterone
- Pregnenolone
- Cholesterol
- Control of Steroidogenesis
- GnRH stimulates release of LH and FSH (low-pulse
requency for FSH, high pulse-rate for LH)
- LH increases testosterone production
- Conversion to oestradiol in granulosa cells
- Oestradiol inhibits gonadotrophs and GnRH
- Oestradiol inhibits gonadotrophs and GnRH
- Conversion to oestradiol in granulosa cells
- FSH increases oestradiol production in granulosa cells
- LH increases testosterone production
- GnRH stimulates release of LH and FSH (low-pulse
requency for FSH, high pulse-rate for LH)
- Action of Oestrogens
- Development and maintenance
of secondary sex characteristics
- Stimulation of breast development during puberty/pregnancy
- Maintain structure and secretory
function of vaginal mucosa
- Promote uterine development
(stimulate endometrial cell proliferation)
- Increase libido
- Important for bone health
- Development and maintenance
of secondary sex characteristics
- Actions of Progesterone
- Maintenance of pregnancy
- Normally inhibits the proliferative effects of oestrogens
- Facilitates ovulation
- Maintenance of pregnancy
- Ovarian Peptide Hormones
- Inhibin
- Secreted by granulosa and
theca cells of developing follicle
- Increases FSH release
- Secreted by granulosa and
theca cells of developing follicle
- Relaxin
- Stimulates follicular development
and oocyte maturation
- May have a role in implantation
- May have a role in implantation
- Stimulates follicular development
and oocyte maturation
- Activin
- Produced by ovary and endometrium
- May have a role in
endometrial development
- May have a role in
endometrial development
- Produced by ovary and endometrium
- Inhibin
- Menstrual Cycle
- Generallly 28 days
- 2 phases
- Follicular phase
- Variable length
- Variable length
- Luteal phase
- Always 14 days
- Always 14 days
- Follicular phase
- Ovulation occurs halfway through
the cycle - between the phases
- LH and FSH remain at a low level and peak at
ovulation. LH levels are higher than FSH levels
- Oestradiol levels increase until a peak at ovulation,
second smaller, less steep peak starts at ~day 17
- Progesterone increases rapidly immediately after ovulation,
plateaus between days 17-25 before a sharp decrease to a low level
- The endometrium grows between days
5-14 and breaks down between days 1-5
- Mean body temperature increases during ovulation
- Generallly 28 days
- Ovulation
- Occurs on day 14
- Preceded by an increase in oestrogen
- Triggers a GnRH/LH surge
- LH surge stimulates ovulation
- Increases synthesis of COX2 - involved in
prostaglandin synthesis (especially PGEs)
- Bind to EP2 receptor - increases cAMP
- COX2/EP2 knockout mice can't ovulate
- Bind to EP2 receptor - increases cAMP
- Increases synthesis of COX2 - involved in
prostaglandin synthesis (especially PGEs)
- Acts on GnRH secreting neurones in the hypothalamus
- Not a direct action of oestrogen - mediated
by oestrogen-responsive neurones
- Use kisspeptin as a transmitter
- Kisspeptin stimulates GnRH release
- Kisspeptin stimulates GnRH release
- Use kisspeptin as a transmitter
- Not a direct action of oestrogen - mediated
by oestrogen-responsive neurones
- LH surge stimulates ovulation
- Triggers a GnRH/LH surge
- Positive feedback
- Occurs on day 14
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