Functions of ovarian hormones

Ovarian hormones Estrogens Progestins 3 estrogens are produces in significant quantities from the ovaries β-estradiol Estrone Estriol β-estradiol is the most abundant and potent Progestins Progesterone 17-α-hydroxyprogesterone Progesterone is the most potent and abundant

Ovarian hormones

General functions ovarian hormones Functions of estrogens Proliferations and growth of endometrial cells Development of secondary sex characteristics of female Onset of labor Functions of progestins Preparation of uterus for pregnancy Maintenance of pregnancy Preparation of breast for lactation

FUNCTIONS OF ESTROGENS

Functions of estrogens Enlargement of sex organs At puberty the female sex organs change to adult shape and size Ovaries Uterus 2-3 fold increase in size Monthly endometrial growth Fallopian tubes Vagina Vaginal epithelium changes from cuboidal to stratified type External genitalia Deposition of fat in mons pubis and labia majora

Functions of estrogens Uterus Proliferative phase of endometrial cycle In pregnancy has important effect on myometrium ↑ gap junctions between myometrial cells ↑ contractility of the myometrium ↑ Braxton Hicks contraction Helps the onset of labor

Functions of estrogens Fallopian tubes Effects similar to the effects in endometrium Proliferation of all the lining cells Proliferation of glandular tissue ↑ No of ciliated cells ↑ activity of cilia - beating toward the uterus Help the propagation of fertilized ovum towards the uterus

Functions of estrogens Breast Development of the stromal tissue Growth of extensive ductile system Deposition of fat Very slight development of lobule and alveoli (this is brought about by progesterone and Prolactin) Characteristic growth and external appearance Male breast can also develop similarly if sufficient female hormones are provided specially up to the age of 20 years

Functions of estrogens Skeleton ↓ osteoclastic activity ↑ osteoblastic activity Accelerated growth at puberty Quick union of epiphysis with the shaft of long bones This effect is stronger than similar effect of testosterone Absence of ovarian hormones → very tall female eunuchs

Functions of estrogens Skeleton (cont..) After menopause ↑ osteoclastic activity ↓ osteoblastic activity ↓ bone matrix ↓ Ca and PO4 deposition Osteoporosis Weak bones Easy fracture Hormone replacement therapy (HRT) does help to prevent or treat osteoporosis

Functions of estrogens Proteins ↑ protein deposition (not very strong effect) Slight +ve nitrogen balance Primarily due to proliferation of cells in many female organs and bone matrix formation Testosterone in male is very strong protein anabolic hormone as compared to estrogen

Functions of estrogens Fats Deposition of fat in Most of the subcutaneous fat cells Breasts Thighs Buttocks Female fat deposition gives characteristic feminine figure to female body Percentage of fat in female body much more than males Metabolic rate is increased but not as much as by testosterone in male

Functions of estrogens Hair distribution No great effect on hair growth or distribution Pubic hair growth at puberty is also probably due to more androgens from adrenal cortices and may be from theca cells a well Skin ↑ thickness Soft and smooth texture ↑ vasularity→ Hyperemic compared to male ↑ Warmth ↑ Bleeding when cut

Functions of estrogens Water and electrolyte Similar to all steroids Sodium and water retention by the kidney tubules The effect is not significant in normal endometrial cycle In pregnancy this effect becomes important Very high level of estrogen produces from placenta Increase in blood volume and salts required during pregnancy

FUNCTIONS OF PROGESTERONE

Functions of Progesterone Uterus Secretory changes in the endometrium Glandular growth Deposition of nutrients in the stromal cells Secretion by endometrial glands Preparation for implantation ↓ contractility of the Myometrium Opposes the contractile effect of estrogen Prevents the expulsion of implanted ovum Maintains pregnancy

Functions of Progesterone Breast Secretory changes Development of lobules and alveoli Cells of gland to proliferate and enlarge Appearance of granules in glandular cells Swelling due to increased fluid in subcutaneous tissue Actual milk secretion does not occur (Prolactin is required for milk secretion)

Functions of Progesterone Fallopian tubes ↑ glandular secretion from mucosal lining Provides nutrition to dividing fertilized ovum which remains in the fallopian tubes for 3-4 days Relaxation of muscles of isthmus to allow entry of fertilized ovum into the uterus

Functions of Progesterone Protein Slightly protein catabolic hormone Mobilization of amino acids Important in pregnancy

Functions of Progesterone Electrolytes Like all steroids electrolyte conservation Competes with Aldosterone Far less potent than Aldosterone Practically causes more loss of sodium Specially important in pregnancy

Endometrial cycle

Phases of endometrial cycle Proliferative phase (Estrogen phase) Secretory phase (Progestational phase) Menstrual phase (Menstruation)

The Uterine Wall

Proliferative Phase At the beginning of the cycle (after menstruation) endometrium is completely desquamated Only a thin layer of endometrial stromal cells left Epithelial cells are present only in remaining deeper portions and crypts of endometrial glands Follicular phase of ovarian cycle starts secretion of estrogen The estrogen is responsible for this proliferative phase of endometrial cycle

The Endometrial Cycle

Proliferative Phase Estrogen (from follicular phase) causes Proliferation of stromal cells Proliferation of epithelial cells Re-epithelialization in 4-7 days after beginning of menstruation Growth of glands and blood vessels Great increase in the thickness of endometrium Cervical gland (other endometrial glands as well) produce strings of mucus Thickness of endometrium reaches 3-5 mm till the time of ovulation

Secretory phase Occurs after ovulation Corpus luteum secretes both estrogen and progesterone Estrogen continues the proliferative changes Progesterone brings about additional changes in the endometrium

Variations in the female hormones

Secretory phase Progesterone causes Marked swelling and secretory development Glands grow more and become tortuous Appearance of secretory substances in the glandular cells Deposition of lipids and glycogen in the stromal cells Further growth and tortuosity of the blood vessels Thickness of endometrium 6-8 mm

The Endometrial Cycle

Secretory phase Endometrium is now well prepared for implantation Endometrial gland secrete “Uterine milk” for nutrition of fertilized ovum even before implantation Entry of ovum 3-4 days after ovulation Implantation 7-9 days after ovulation Endometrium contain large amount of nutrients for implanted fertilized ovum Trophoblastic cells at the implantation sites can digest and absorb the stromal cells nutrients for the embryo

The Endometrial Cycle Figure 28.20

Menstrual phase If fertilization does not occur Corpus luteum involutes on 12th day of ovulation Absence of estrogen and progesterone Necrotic changes in the endometrium Shedding of endometrium Menstrual flow

Menstrual phase Absence of progesterone (& estrogen) ↓stimulation of endometrium →regression of thickness to 65% Vasospasm of the endometrial blood vessels Due to prostaglandins or other vasoconstrictors Vasospasm → ↓nutrition Necrosis of blood vessels Seepage of blood in many areas Growth of hemorrhagic areas Necrotic outer layers separated from basal layers

Menstrual phase Menstrual flow starts Within 48 hours all the endometrium is desquamated The necrotic tissue in the uterine cavity Onset of uterine contraction by prostaglandins Expulsion of contents About 40 ml blood loss About 35 ml serous fluid loss Fibrinolysin in the necrotic tissue in the menstrual blood prevent clotting Excessive bleeding may cause passage of clots Clots usually sign of pathology After 4-7 days new cycle of proliferation starts

The Uterine Wall

Leucorrhea during menstruation Chemotactic substances in the necrotic tissue Large number of WBCs passed in the menstrual blood Uterus is resistant to infections in spite of denuded, desquamated surface of endometrium

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