menstrual cycle

1. • Physiology of menstrual cycle

2. Definition
 The cyclic events that take place in a
rhythmic fashion during the reproductive
period of a woman’s life is called menstrual
cycle.
  MC starts at the age of 12-15 years.
  First occurrence of menstruation called
menarche
  Permanent cessation of MC is called
menopause(45-50 years)
  Duration of menstrual cycle- 28 – 35 days.

3. Changes during menstrual cycle:
  Ovarian changes
  Uterine changes
  Vaginal changes
  Changes in cervix

4. Ovarian changes
 :
 Occurs in two phases
  Follicular phase
  Luteal phase

5. Follicular phase:
 Extends from the 5th day of the cycle
until the time of ovulation, which takes
place on 14th day.
 There is Maturation of ovum with
development of ovarian follicles through
different stages.

6. Ovarian follicles
  They are the glandular structures
occupying the stroma of cortex.
  Each follicle consists of the ovum
surrounded by epithelial cells namely
granulosa cells.
  The follicles gradually grow into a
matured follicle through various stages.
Various stages are -  Primordial follicle 
Primary  Vesicular  Matured or graffian
follicle

7. Changes in granulosa cells.
 Proliferation of granulosa cells occurs.
 Some irregular spaces appear in between the granulosa cells.
 These spaces fuse to form a cavity called follicular cavity or
antrum.
 Antrum is filled with a serous fluid called the liquor folliculi.
 Increase in size of antrum and follicle.
 Ovum is pushed to one side and surrounded by granulosa
cells which forms the germ hill,.
 Granulosa cells which line the antrum form membrane
granulosa.
 Cells of germ hill become columnar and form corona radiata

8. Changes in ovum
 Ovum increases in size.
 Nucleus become larger and vesicular
 Cytoplasm become granular
 Thick membrane called zona pellucida
formed around the ovum.
 A narrow cleft appears between ovum and
zona pellucida. Cleft is called perivitelline
space.

9. Formation of capsule
 A covering sheath is formed around the
follicle known as follicular sheath or theca
folliculi.
 The theca folliculi divides into 2 layers
 Theca interna-inner vascular layer.it
contains epithelial cells which secretes
female sex hormones especially estrogen.
 Theca externa –outer layer of follicular
capsule

11. Graafian follicle
GF is the matured ovarian follicle with
maturing ovum.
Changes are-
 Increase in size
 Zona pellucida ,theca interna becomes thick
 At one point, the follicle protrudes upon the
surface of the ovary called stigma.
 More epithelial cells start secreting female
sex hormones.
 On the 14th day of MC ,GF is ready for the
process of ovulation.

14. Ovulation
 Ovulation is the process by which the
graafian follicle in the ovary ruptures and,
the ovum is released into the abdominal
cavity. Occurs on the 14th day of
menstrual cycle in a normal cycle of 28
days.

15. Process of ovulation
 Rupture of graafian follicles takes place at the stigma
 Follicular fluid oozes out.  Germ hillock is freed
from wall.
 Ovum is expelled out into the abdominal cavity along
with some amount of fluid and granulosa cells.
 From abdominal cavity, the ovum enters the fallopian
tube through the fimbriated end. After fertilization
,the ovum is called zygote.
 From fallopian tube ,the zygote reaches the uterus on
3rd day after ovulation
 If fertilization doesnot occur, the ovum degenerates

17. Determination of ovulation time
 Daily recording of basal body temperature.
There will be a rise of 0.5 C above normal after
ovulation.
 Endometrial biopsy specimen shows secretory
changes if ovulation has occurred
 Cervical mucus will be thick and cellular after
ovulation. Fern pattern will be absent after
ovulation.
 Estimation of blood FSH and LH shows high
values at the time of ovulation.
 Lower abdominal pain in the midcycle
indicates ovulation.

18. Luteal phase
 This Phase extends between 15th and 28th day of
menstrual cycle.
 During this phase corpus luteum is developed and
hence this phase is called luteal phase.
 After the ovum is released, the follicle is filled with
blood which is called as corpus hemorrhagicum.
 Granulosa cells proliferate and cavity gets filled
with lipid rich luteal cells which is called as corpus
luteum / or yellow body.
 Functions-Corpus luteum secretes estrogen,
progesterone, inhibin and relaxin.it also help for
maintaining pregnancy by the hormones secreted by
corpus luteum until placenta starts secreting
estrogen and progesterone

19. Fate of corpus luteum:
 If the ovum is not fertilized,corpus luteum starts
degenerating and forms corpus luteum
menstrualis. Afterwards, by about the 28th day, it
forms a whitish scar called corpus albicans. Now
there is no secretion of estrogen and progesterone
and next cycle begins.
 If fertilization occurs, the corpus luteum is
maintained by HCG (from syncitiotrophoblast)
,which is essential for the maintenance of
pregnancy. After 3 months ,placenta starts
secreting hormones and corpus luteum
degenerates

21. Uterine changes
 Uterine changes - occurs in 3 phases
 Menstrual phase
 Proliferative phase
 Secretory phase.

23. Menstrual phase
 After ovulation ,if fertilization doesnot occur,the ovum becomes zygote and
it gets implanted on the uterine wall leading to pregnancy.
 If pregnancy doesnot occur,the thickened endometrium is shed or
desquamated.
 This desquamated endometrium is expelled out through vagina along with
some blood and tissue fluid.
 The process of shedding and exit of uterine lining along with blood and
fluid is called menstruation or menstrual bleeding.
 This period is called menstrual phase or menstrual period.
 The day when bleeding starts is considered as the first day of the menstrual
cycle.
 Menstruation occurs when there is sudden reduction in the release of
estrogen and progesterone .
 Menstruation stops between 3rd and 7th day of menstrual cycle.
 At the end of menstrual phase,the thickness of endometrium is only about
1mm.

24. Proliferative phase
 PP extends usually from 5-14th day of
menstruation .
 It corresponds to the follicular phase of ovarian
cycle.
 The endometrial cells proliferates, so that the
endometrium reaches the thickness of 3-4 mm at
the end of proliferative phase.
 Uterine changes during proliferative phase occur
because of the influence of estrogen released from
ovary.
 On 14th day ,ovulation occurs under the influence
of LH followed by secretory phase

25. Secretory phase
 Extend between 15th and 28th day of the menstrual cycle.
 After ovulation, corpus luteum is developed in the ovary.
 It secretes a large quantity of progesterone along with a small
amount of estrogen.
 Estrogen is responsible for repair of damaged endometrium
and growth of glands.
 Progesterone is responsible for the further growth of
endometrial glands and secretory activities in the
endometrium.
 If fertilization occurs, further changes occur in the uterus for
the survival of the developing fetus. if the ovum unfertilized,
menstruation occurs after this phase and a new cycle begins

26. Changes in cervix
 Proliferative phase -Under the influence
of estrogen, the mucus membrane of
cervix becomes thinner and alkaline.
 Secretory phase - Because of progesterone
action, the mucus membrane of cervix
becomes more thick and adhesive.

27. Vaginal changes
 Proliferative phase - The epithelial cells of
vagina are cornfied because of the action
of estrogen.
 Secretory phase - Vaginal epithelium
proliferates due to the action of
progesterone.

28. Hormonal regulation of menstrual cycle
 Hormones involved in regulation
 Hypothalamic hormone-GnRH
 Anterior pituitary hormones- FSH and LH
 Ovarian hormones- estrogen and
progesterone