Female Reproductive Endocrinology

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Female Reproductive Endocrinology

• Pituitary-Hypothalamus Control of Cycle
• Female Menstrual Cycle
• Ovarian Granulosa Cells
• Ovarian Thecal Cells
• Actions of Estrogens
• Actions of Progesterone
• Fetoplacental Hormones

LKS
2
Events Leading to the LH Surge
1. During the Proliferative Phase of the
Menstrual Cycle (about day -7) the concentration
of E2 rises as the ovary produces and secretes
it in response to Ant. Pit. FSH. 2. An
increase in estradiol (E2) leads to an inhibition
of both the Hypothalamus GnRH producing cells
and the Anterior Pituitary gonadotropic cells.
In the Ant. Pit. this inhibition to GnRH
hypersensitizes the gonadotropic cells to GnRH,
But they cannot respond because of the presence
of E2. 3. Just before the LH surge, the
concentration of E2 decreases, releasing the
inhibition on the Ant. Pit. To GnRH. 4. GnRH
hyperstimulates the hypersensitized Anterior
Pituitary and the response is to hypersecrete LH.
There is no progesterone to inhibit LH so all is
secreted.
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Events Leading to LH Surge 2
5. FSH does not surge quite as much due to the
fact that there is still E2 present in the
plasma and at the Ant. Pit. So the FSH peak is
blunted due to negative inhibition on the FSH
release. 6. Thus there is the LH surge, which
stimulates the formation of the Corpus Luteum and
also leads to ovulation.
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Pituitary - Hypothalamus Control of Female
Reproductive Function
GnRH
Hypothalamus
()
LH
FSH
Pituitary
(-)
Ovaries
Granulosa Cells
Thecal Cells
Progesterone
Estradiol
LKS
5
Female Reproduct-
LH
Prog
E2

LH
ive Cycle
pg / ml
ng / ml
FSH
mIU/ ml
80
10
1000
60
Prog
40
500
5
Estradiol
FSH
20
14
Days
-14
-7
7
0
Follicular Phase - Proliferation
Corpus Luteum - Secretory Phase
Ovulation
LKS
6
Embryology of Sex Tissues (1)Male
Female

• Stromal Cells become
• Leydig Cells
• Supporting Cells become
• Sertoli Cells

• Stromal Cells become
• Thecal Cells
• Supporting Cells become
• Granulosa Cells

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Embryology of Sex Tissues (2)Male
Female

• Wolffian Ducts become
• epididymus
• vas deferens
• seminal vessicles
• ejaculatory duct
• Mullerian Ducts (in presence of Mullerian
  Inhibitory Substance MIS Regress)

• Wolffian Ducts Regress
• Mullerian Ducts become
• fallopian tubes
• uterus
• upper 1/3 of vagina

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Embryology of Sex Tissues (3)Male
Female

• Genital tubercle,fold, swelling Urogenital ridge
  Become (In the Presence of dihydrotestosterone)
• Penis
• Scrotum
• Prostate gland

• Genital tubercle,fold, swelling Urogenital ridge
  Become (In the absence of dihydrotestosterone)
• Labia majora
• Labia Minora
• Clitorus
• Lower 2/3 of vagina

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Ovarian Granulosa Cells

• Responds to FSH
• Converts Androstenedione to Estradiol
• Secretes Estradiol
• Produces Plasminogen Activator
• Produces Plasmin

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Ovarian Thecal Cells

• Respond to Pituitary LH
• Convert Cholesterol to Androgens and Estradiol
• Provide Androstenedione to Granulosa Cells
• Produce Collagenase
• Collagenase Plasmin Follicular Rupture

LKS
11
Actions of Estrogens 1

• Stimulation of Female Sex Organs (Uterus,
  fallopian tubes, vagina, mammary glands)
• Stimulate Follicular growth
• Stimulate Granulosa cell-LH receptor formation
• Stimulate secretions (Mucous, sebacous glands)

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Actions of Estrogens 2

• Stimulate Bone Growth, Epiphysial Plate Closure
• - serum cholesterol, - glucose tolerance
• serum HDL, TBG, ShBG (TeBG), Progesterone
  receptors in CL

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Actions of Progesterone

• Stimulates Secretory Endometrium
• Stimulates Mammary growth development
• - Uterine motility, - sodium retention
• Ventilation, Body temperature

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Fetoplacental Endocrine Unit

• Placenta
• Fetal Adrenal Cortex
• Fetal Liver

LKS
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Fetoplacental Compounds Produced

• Alpha Fetoprotein (non-endocrine)
• Human Chorionic Gonadotrophin
• stim. steroidogenesis in CL
• Human Placental Lactogen (human chorionic
  somatomammotrophin)
• lipolytic, insulin antagonistic, stim. mammary
  growth and development
• Parathyroid hormone related protein-PTHrP

LKS