2. Menstruation
• Definition: The visible manifestation of cyclic
physiologic uterine bleeding due to shedding
of the endometrium.
• Due to invisible interplay of hormones
through hypo-thalamo-pituitary-ovarian axis.
• For menstruation to occur axis should be
active , endometrium should be receptive and
outflow tract should be patent.
3. Menstrual Cycle
• The period extending from first day of period
until the 1st day of next period.
• Normal length of a cycle is between 28-32
days. Mean – 28 days.
• It occurs cyclically between 21-35 days.
• Menarche: First menstruation
• Age of onset – 11-15 years &average is 13
years
4. Ovaries
Reproductive tract
Other targets
Steroids
Feedback
Hypothalamus
GnRH (gonadotrophin
releasing hormone)
Pituitary
LH
FSH
+ (“gonadotrophins”)
Menstruation is an
external indicator of
ovarian events controlled
by the hypothalamic-
pituitary axis
Roles of the ovary
1. Gametes (ova)
2. Hormones
MENSTRUATION
(oestradiol,
progesterone).
5. • Menstruation ceases between 45-50 years.
• Duration – 4-5 days
• Amount – 20-80 ml
• Menstrual discharge consists of blood, mucus,
epithelial cells, fragments of endometrium,
prostaglandins, enzymes and bacteria.
6. • Menstrual cycle is divided into
• 1] Ovarian
• 2] Endometrial cycle
7. 0 4 8 12 16 20 24 28
Timing events in the menstrual cycle.
2. LH surge
Day 1
Menstruation
Day 1
LH
OVULATION
Days before Days after
Follicular phase Luteal phase
8. Ovarian Cycle
• Development and maturation of a follicle,
ovulation and formation of corpus luteum and its
degeneration
• All these events occur in 4 weeks
• 1] Recruitment of group of follicles
• 2] Selection and maturation of dominant follicle
• 3] Ovulation
• 4] Corpus luteum formation and degeneration
9. Recruitment of Follicles
• Out of many primordial follicles only 20 antral
follicles are developed in each cycle.
• All these follicles from 2-5 mm size are influenced
by FSH.
• Those follicles not influenced by FSH will become
atretic.
• Oocyte of each follicle grow out of
proportion.Oocyte is surrounded by acellular
glycoprotein from follicular cells called Zona
pellucida
10. • Flattened outer pregranulosa cells will
become Granulosa cells. These cells contain
FSH receptors.
11. Selection of a Dominant follicle and
maturation
• Dominant follicle is called as Graafian Follicle
out of 30-50 follicles from many primordial
follicle.
• Starts from 5-7 days
• Follicle with high oestrogen and with
maximum FSH receptors in granulosa cells will
become a dominant one.
• Rest of follicles will become atretic by 8th day.
12. 0 4 8 12 16 20 24 28
LH
Day 1
Menstruation
OVULATION
Animated ovarian events
Oestradiol
1. Follicular
growth
Key events in the ovarian cycle
14. Menstruation
Ovulation
How many follicles are
growing at the start of the
cycle?
Many! 30-50
When do
follicles start
growing?
2-3
months
earlier!
Why is only 1 selected
and becomes
“dominant”?
17. • Cumulus oophorus or Discus proligerous anchors
the ovum to to the wall of follicle
• Corona radiata – radially arranged cells around
the ovum
• At this stage FSH induces LH receptors in
granulosa cells of dominant follicle
• LH receptor induction is essential for mid cycle LH
surge for ovulation and lutenisation of granulosa
cells to form corpus luteum and secretion of
progesterone
18. Graafian Follicle
• Graafian follicle measures 20 mm before
ovulation
• It has following layers from outside inward
• 1] Theca externa
• 2] Theca interna
• 3] Membrana granulosa
• 4] granulosa cell layer
• 5] discus proligerous
• 6] corona radiata woth ovum inside
• And 7] antrum with fluid
21. Time for development of a Follicle
• Total duration - 3 months
• Upto antral stage of 1mm – 2months
• Upto 5 mm stage – 2 weeks
• Upto 20 mm – 2 weeks
22. Ovulation
• Causes:
• 1] LH surge – secondary to sustained peak
level of estrogens in the late follicular phase.
This will cause completion of reduction
division in the oocyte and lutenisation of
granulosa cells, synthesise progesterone
andprostaglandins.
• 2] FSH rise- leads to plasminogen and it helps
in lysis of follicle.
23. • 3] Stretching factor – Necrobiosis of wall due
to passive stretching
• 4] Contraction of micromuscles in theca
externa
24. Effects of Ovulation
• Following ovulation the follicle is changed to
corpus luteum.
• Ovum will be picked up by fallopian tube and
may fertilise or degenerate.
25. Corpus Luteum
• Life cycle is divided into 4 stages:
• 1] stage of proliferation
• 2] stage of vascularisation
• 3] stage of maturation and
• 4] stage of regression
26. • Stage of Proliferation:
• Granulosa cells will become polyhedral and enlarged and
with lipids –looks greyish yellow called granulosa lutein
cells
• Stage of vascularisation: small capillaries grow towards
granulosa layer.
• Stage of maturation:
• After 1 week reaches 1-2cm and a carotene pigment will
give a yellow color
• Stage of regression: on 22 -23 day regression starts.Lutein
cells become atrophic and will become white called Corpus
Albicans / if pregnancy occurs it will become Corpus
luteum of pregnancy.
27. Hormones for formation and
maintenance of corpus luteum
• 1] FSH induces LH receptors and LH surge
causes lutenisation of granulosa cells and
progesterone secretion.LH scretion should be
continuous for function of corpus luteum
• 2]17 alfa–OH–progesterone and estradiol
• 3] Low level of prolactin
• Life span of Corpus luteum is 12-14 days.
28. Hormones from Corpus luteum
• 1] Progesterone
• 2] Oestrogen
• 3] Inhibin
• 4] Relaxin
• In absence of pregnancy levels of O+P+I
decreases leading to rise in FSH and this in
turn leads to recruitment of new follicles
30. Endometrial or Uterine Cycle
• Endometrium contains
• surface epithelium,
• glands,
• stroma and
• blood vessels
• Endometrium has 2 zones:
• 1] Basal [ stratum basalis ]
• 2] Superficial functional zone
31. 0 4 8 12 16 20 24 28
Uterine changes in the menstrual cycle.
Menstruation
OVULATION
Oestradiol
causes an
increase in
thickness (the
“proliferative
phase”)
More secretion from
the glands – hence
the term “secretory
phase”
Endometrial
depth
32. 0 4 8 12 16 20 24 28
Menstruation
Characteristic “spiral arteries”
Terminal differentiation of
stromal cells – “decidualisation”
Optimal time for
implantation
33. • Stratum Basalis:[ 1mm ]
• Ocupies 1/3 of endometrium – basal arteries+
• Not influenced by hormones
• Regeneration occurs from it.
• Functional zone:
• Responds to hormones like O+P
• In an ovulatory cycle four stages are seen.
34. Functional Zone stages
• 1] Stage of regeneration
• 2] Stage of Proliferation
• 3] Secretory phase
• 4] Menstrual phase
35. • Stage of regeneration:
• Starts before menstruation and completes after 2-3
days after periods. Measures 2mm.
• Glands are lined by cubical cells
• Stage of Proliferation:
• Extends from 5-6th day to 14th day due to
Estrogens.Glands are tubular and perpendicular to
surface.
• Epithelium is columnar with nuclei at base, stromal
cells are spindle shaped with spiral vessels upto
epithelium. Subepithelial congestion +. Measures 3-4
mm.
36. • Secretory Phase:
• Effects of O+P
• Oestrogen induces Progesterone receptors and
progesterone is responsible for secretory phase.
• Starts at 15th day to 5-6 days prior to
menstruation.
• Epithelium is more columnar and ciliated.
• Glands increase in size with taller epithelium with
vacuoles formation- subnuclear vacuolation.
37. • First and earliest effect of progesterone is
appearence of subnucleolar vacuolation.It will
persist upto 21 days.
• Saw toothed glandular epithelium, glands
become corkscrew shaped with marked spiralling
of vessels.
• Measures 6-8 mm.
• Regresssion of endometrium starts 24-48 hrs
prior to periods.
• Marked spiralling of vessels and withdrawl of
hormones causes tissue hypoxia and anoxia.
38. Menstrual phase
• Degeneration and casting off endometrium
due to regression of corpus luteum with fall in
level of O+P.
• Degeneration is due to stasis of blood and
spasm of vessels leading to damage of vessels
with escape of blood.
• Proteolytic enzymes from lysosomes causes
local damage.[ Enzymatic autodigestion ]
39. What causes the onset of menstruation?
Steroid
levels
fall This is followed by
the onset of
menstruation
40. How does menstruation stop?
• Prolonged vasoconstriction
• Myometrial contraction
• Local aggregation of platelets
• Endothelin and platelet activating factor are
potent vasoconstrictors.
42. Hormones of ovarian and
endometrial cycle
• At menstruation Oestrogen and inhibin are at low levels and high
FSH.
• Oestrogen increases gradually and FSH decreases and remains static
at day 5.
• O+ LH and androgen increases.
• Matuaration of follicle is combined effect of FSH and LH/
• Peptides –Inhibin, Activin and Follistatin
• Growth Facors – IGF, EGF from theca cells – modulate FSH,LH and
peptide actions.
• IGF stimulates aromatase activity and progesterone synthesis.
• Progesterone will increase in secretory phase until 5 days before
periods.
• LH will start declining
43. Hormones and Ovulation
• It occurs after 10-12 hrs following LH surge.
• It occurs after 24-36 hrs following Oestradiol
peak of 200 pg/ml
• Progesterone peaks at 8th day after LH surge.
44. • Datting of endometrium – Examination of
endometrium
• Luteal phase defect – A discrepancy of more
than 2 days in the postovulatory phase when
endometrium is examined
• A woman can have periods without ovulation.
45. 0 4 8 12 16 20 24 28
Cervical mucus
Menstruation
OVULATION
Cervical
mucus
Variable
number of
“dry” days
Production
of low
viscosity
mucus
increases
Abundant mucus - like
“raw egg white”
Thick, rubbery, high viscosity
- impenetrable to sperm.
46. With increasing oestradiol:
1. The mucus becomes more abundant - up to
30x more and its water content increases.
2. Its pH becomes alkaline.
3. Increased elasticity – ("spinnbarkeit test")
5. “Ferning pattern” caused by the interaction of
high concentrations of salt and water with
the glycoproteins in the mucus.
Characteristic fernlike pattern as
the mucus dries on a glass slide.
47. 0 4 8 12 16 20 24 28
Menstruation
OVULATION
LH
36
36.2
36.4
36.6
36.8
37
37.2
37.4
37.6
37.8
38
A small (0.5 oC) rise in BBT
typically follows ovulation.
Basal body temperature
48. Basal body temperature
Plasma oestradiol
Plasma progesterone
Volume of cervical mucus – and
sperm penetration
Uterine endometrium
49. a) Calendar Method - which is essentially based on the
previous menstrual history.
b) Temperature method - using a midcycle rise in body
temperature as a sign when ovulation has occurred.
c) Cervical changes - which can be detected by feeling the
cervix and cervical mucus.
d) Hormonal methods - using over-the-counter "kits" to
assess urinary hormone levels.
There are a number of potential ways of trying to identify the
“fertile” period..: