Dr Ismaiel Abu Mahfouz Menstruation Definition A womans monthly bleeding from the reproductive tract induced by hormonal changes of menstrual cycle For menstruation to occur Coordinated HPO axis ID: 776633
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Slide1
The menstrual cycle
Dr Ismaiel Abu Mahfouz
Slide2Menstruation
Definition
A woman's
monthly bleeding
from the reproductive
tract
induced by hormonal changes
of menstrual
cycle
For menstruation to
occur
Coordinated HPO axis
Responsive endometrium
Patent outflow
Slide3The menstrual cycle hormones
Slide4GnRH
A peptide hormone
Synthesized
and released
from
GnRH neurons in
hypothalamus
Responsible for the release of FSH & LH from
anterior pituitary
Slide5FSH
A glycoprotein polypeptide hormoneGranulosa cell proliferation and differentiationAntral follicle developmentOestrogen productionInhibin synthesisInduction of LH receptors on dominant follicle
Slide6LH
A glycoprotein hormone
The
main promoter of constant androgen
production
from the theca cell
The
pre-ovulatory LH surge
Triggers ovulation
and follicular
rupture
Induces resumption
of oocyte meiotic
maturation
Causes luteinization
of granulosa
cells (formation of corpus luteum)
Slide7Estradiol
Suppresses FSH due to a -ve feedback leading to
selection
of a dominant follicle
Triggers
LH
surge due to a +ve
feedback
Increases
endometrial thickness
Stimulates
cervical glands
to secrete a particular type of mucus which is essential for
sperms
to pass
through
Slide8Progesterone
Induces secretory endometrium
to
enhance embryo implantation
Maintains
endometrium in
1
st
week of pregnancy
Modifies endometrial glandular
structure (
more number, more tortuous)
Involved
in gene expression in endometrium needed
for
implantation
Slide9Inhibin
Two hormones : Inhibin A & B
Secreted by granulosa cells in ovary
Inhibits production of FSH via –ve feedback
Involved in control of gamete production,
embryonic and fetal development
Slide10Two-cell hypothesis of oestrogen production
Slide11Hormonal interaction
Slide12The menstrual cycle
The ovarian cycle
The endometrial cycle
Slide13The ovarian cycle
Slide14The Ovarian Cycle
Follicular phase (pre-ovulatory
)
Recruitment & selection of dominant
follicle
Increasing levels of estradiol & inhibin
B
Ovulatory
phase
LH surge
Rupture of
pre-ovulatory
follicle wall
Release of viable ovum
Luteal phase (post-ovulatory
)
Corpus
luteum development
Increasing levels of
progesterone
Secretory
changes in
endometrium
Menstrual phase
Slide15Follicular Phase
A group of the most mature follicles (called “antral
follicles
”) are
recruited
Only
follicles
most sensitive to FSH
undergoes
a
further development
Follicle
most sensitive to FSH continue to
develop
and produce a large amount of estradiol
and
inhibin
B
Remaining
follicles become
atretic
(99
%)
Slide16Ovulatory phase
An event
in the menstrual cycle by which a
selected mature
follicle breaks and releases a
viable oocyte
Each month, one egg is released
; occasionally
, two or
more
If pregnancy does not occur,
menstruation
starts
after exactly two weeks
Slide17Ovulatory phaseMechanism of follicle rupture
Increase
of
intra-follicular
pressure
Perifollicular ovarian smooth muscle contractions
Vascular alterations in
peri-follicular vessels
Prostaglandins and proteolytic enzymes
Cytokines
, O2 free-radicals,
nitric
oxide and angiotensin II
Slide18Ovulatory phaseOvulation
Ovulation occurs 34-36 hours after onset of LH surge
Slide19Luteal phase
Peak level of progesterone occurs 7 days after ovulation This approximates the time of implantationIn early pregnancy, hCG maintains luteal function with secretion of progesterone until placental steroidogenesis is established
Slide20Dominant follicle
Slide21E2
P
roliferative
changes
E2
dominant endometrium is UNSTABLE
Slide22P
Secretory changes
P dominant endometrium is STABLE
Slide23Menstrual phase
Rapid ↓ in steroids → shedding of the unused
endometrium
Inflammatory mediators (PGs, ILs, and TNF) → vasospasm in
spiral arteries
→ hypoxia and endometrial
devitalisation
Haemostatic
mechanisms
will be activated including
platelet plugs, coagulation cascade, and
fibrinolysis
Endometrium shed down to basalis layer
Slide24Phases of the endometrium
Slide25Endometrial breakdown
Basalis layer remains Undergoes repairEndometrium is protected from the lytic enzymes in the menstrual fluid by mucinous layer of carbohydrate products secreted from glands and stromal cells
Slide26Menstrual Fluid
Autolysed
functionalis layer
Inflammatory exudate
RBC
Proteolytic enzymes
(mainly
plasmin)
If rate and flow
are
high clots are formed
Slide27Estrogen
LHsurge
GnRh
-ve feedback
E
Hypothalamus
FSH
follicle
Ant
. Pituitary
Inhibin
Dominant follicle
Ovulation
-VE
+Ve
Slide28Slide29Cervical changes
Follicular phase
Luteal phase
Internal
os:
funnel shape
Tightly
closed
Mucus:
thin
&watery
Thick
& viscid
Stretchability
:
increased
Lost
Slide30Normal menstrual cycle
Menstrual cycle
should
be
described
according
to
four
specific
symptomatic components
Frequency
Duration
Volume
Regularity
Slide31Normal Menstrual Cycle
Frequency (Length)
Mean is 28 days +/- 7 days
Menstrual
cycle tends to shorten with age
Initially irregular
Duration of menstruation
Normal range: 4.5 – 8.0 days, Mean: 5 days
Prolonged
>8 days, shortened
< 4.5 days
With advancing age: duration decreases
Volume
of menstrual
blood loss (ml)
Range: 20 – 50 mls, Mean
40
ml
Heavy
>80 ml; light
< 5 ml