For medical postgraduates

1. Anuja Mary Sabu
M.Sc Medical Biochemistry (vth Sem)

2. ABOUT…..
› Cyclical event in which there is periodic shedding of uterine endometrium
followed by its proliferation & preparation for implantation.
› Derived from “MENSEM - a month”
› Characteristic of primates (humans, apes & monkeys)
› Other vertebrates –Estrous cycle
› Menarche – beginning of menstrual cycle (11-13yrs)
› Menopause - cessation of menstrual cycle (45-52yrs)

3. DURATION OF MENSTRUAL CYCLE
› Length of cycle average about 28 days.
› Is not same in women.
› Normally, it ranges from 21 to 35 days.
› Cycle becomes irregular towards menopause.
› Irregularities indicates dysfunctions of reproductive system.
› Physiologically, MC temporarily ceases during pregnancy & lactation.

4. PHASES OF MENSTRUAL CYCLE

5. HORMONES INVOLVED IN VARIOUS PHASES

7. Follicular
phase
Primordial
Granulosa
Preantral
Zona pellucida Theca cells
Antrum
Secondary
follicle
Early antral
stage
Dominant
follicle
Late antral
Corona radiate
&cumulus
oophorus
Grafian follicle
20 oocyte to
flow freely in
the antrum
Luteal phase
begins with
ovulation
Grafian
follicles
ruptures
Corpus luteum
Estrogen &
progesterone
20 oocyte
travels to
uterine tube
Degenerates
Corpus
albicans
Estrogen &
progesterone
Setting stage for
menstruation &
next follicular
phase
Follicular
phase
Primordial
Granulosa
Preantral
Zona pellucida Theca cells
Antrum
Secondary
follicle
Early antral
stage
Dominant
follicle
Late antral
Corona radiate
&cumulus
oophorus
Grafian follicle
20 oocyte to
flow freely in
the antrum
Luteal phase
begins with
ovulation
Grafian
follicles
ruptures
Corpus luteum
Estrogen &
progesterone
Degenerates
Follicular
phase
Primordial
Granulosa
Preantral
Zona pellucida Theca cells
Antrum
Secondary
follicle
Early antral
stage
Dominant
follicle
Late antral
Corona radiate
&cumulus
oophorus
Grafian follicle
20 oocyte to
flow freely in
the antrum
Luteal phase
begins with
ovulation
Grafian
follicles
ruptures
Corpus luteum
Estrogen &
progesterone
Degenerates

9. UTERINE CYCLE

10. Uterine cycle Menstrual phase Menstruation
Decreased blood in
endometrial tissue causes
tissue to die & slough into
vagina
Menstrual flowProliferative phase
Uterus prepares for the
fertilised ovum
1.Endometrial lining develops
2.Endo.layer grows
3.Endo.glands enlarge
4.smooth muscle layer thickens
5.cervical glands secrete mucus
Secretory phase
Endometrium prepares for
implantation
1. ↑ blood supply
2.Enlarrged glands that
secrete glycogen fluid
3.Cervical secretions
If fertilization does not
occur, corpus luteum
degenerates
Follicular phase begins
again.
Estrogen levels
causes

12. CHANGES IN REPRODUCTIVE ORGANS IN
MENSTRUAL CYCLE
Changes in follicular phase (Menstrual & Proliferative phase)
1.Ovarian changes
One follicle is selected as dominant follicle (4th day).
Dominant follicle → mature follicle.
Granulosa & theca interna cells proliferate &secrete Estrogen.
Follicle ruptures about 14th day resulting in ovulation.
2.Uterine changes
Layers of uterine endometrium are sloughed.
Thickness of endometrium ↑ from 5th day to 14th day –influence of Estrogen.
Endometrial glands lengthen & glands are drawn out.
Formation of no.of spiral arteries.
Proliferation of endometrium –main feature (preovulatory phase).

13. 3.Uterine cervix changes
Volume of cervical mucus ↑.
Alkalinity & elasticity ↑.
Cervical epithelium becomes more secretory.
Forms spinnbarkeit.
4.Vaginal changes
Vaginal epithelial cells become keratinized

14. Changes in the luteal phase (Secretory phase)
1.Ovarian changes
Follicle is rapidly filled with blood – corpus hemorrhagicum
Granulosa & theca cells –lutenization →lutein cells →corpus luteum
If pregnancy does not occur, it degenerates b/w 26th -28th days –corpus albicans

15. 2.Uterine changes
Progesterone secretion ↑
Estrogen also ↑ to an extent.
Uterine glands become coiled &tortuous.
Glandular cells store glycogen & secrete large quantity of carbohydrate –rich
mucous &fluid.
Vascularity of endometrium ↑.Spiral arteries become tortuous.
3.Changes in cervical mucous
Cervical mucous becomes thick & elasticity ↓.
Sperm cannot enter through progesterone-dominant cervical mucous.
4.Vaginal changes
Vaginal epithelium proliferates & secretes thick mucous.
Keratinization ↓

17. DISORDERS OF MENSTRUAL CYCLE
› Amenorrhea :absence of menstrual cycle.
› Anovulation : absence of ovulation during a menstrual cycle.
› Hypomenorrhea : ↓ menstrual bleeding in duration or amount or both.
› Oligomenorrhea : ↓ frequency (cycle more than 35 days) of MC.
› Dysmenorrhea : Painful menstrual bleeding.
› Menorrhagia : ↑ menstrual bleeding in amount, duration or both.
› Metrorrhagia : Bleeding occurring between the periods.
› Polymenorrhea : MC occurs frequently (<21 days).
› Premenstrual syndrome :development of nonspecific features about a week
before the onset of menstrual bleeding.
› Anorexia nervosa : complex behavioural disorder in women associated with
functional abnormalities.