Menstrual & Ovulatory Cycle
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Transcript of Menstrual & Ovulatory Cycle
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Female Reproductive organs
Primary female
reproductive organsare ovaries whileaccessory are theducts like uterine
tubes, uterus, andvagina
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The Ovaries
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The Ovaries
The ovaries on the outer sideare surrounded by a layer ofepithelial cells called the
germinal epithelium. Embedded in their cortex are
ovarian follicles in variousstages of development.
The remains of rupturedfollicle after ovulation is calledcorpus luteum
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Uterine Tubes
Uterine tubes receive the
ovulated oocyte and provide
a site for fertilization. They
empty into the uterus. They expand distally around
the ovary forming the
ampulla which ends in the
funnel-shaped, ciliatedinfundibulum containing
fingerlike projections called
fimbriae.
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Uterine Tubes
The uterine tubes have nocontact with the ovaries andthe ovulated oocyte is
cast into the peritonealcavity. Beating cilia on thefimbriae create currents tocarry the oocyte into theuterine tube.
The oocyte is carriedtoward the uterus byperistalsis and ciliary actionof the lining ciliaryepithelium of the tube.
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Uterus
The uterus is a hollow,thick-walled organlocated in the pelvisanterior to the rectum andposterio superior to the
urinary bladder. Its partsare
Fundus rounded regionsuperior to the entrance ofthe uterine tubes
Body major portion ofthe uterus
Isthmus narrowedregion between the bodyand cervix
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Uterus
Cervix narrow neck whichprojects into the vaginainferiorly
Cervical canal
cavity ofthe cervix thatcommunicates with: The vagina via the external os
The uterine body via theinternal os
Cervical glands secretemucus that covers theexternal os and blockssperm entry except duringmidcycle
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Ovarian Cycle
Monthly series of events occurring
in ovaries associated with the
maturation of an egg is called an
ovarian cycle. It consists offollicularphase and luteal phase
Follicular phase period offollicle growth (days 114). During it
primordial follicle becomes primary,secondary and tertiary follicles and
follicular cells become granulosa
cells secreting estrogen.
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Ovarian Cycle
Follicular phase cont. The fullsized follicle (vesicular follicle)
bulges from the external surface ofthe ovary. The primary oocyte
completes meiosis I, and the stage
is set for ovulation.
Ovulationoccurs at the mid of thecycle and a twinge of pain is
sometimes felt in pelvis at ovulation
called Mittelschmerz
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Ovarian Cycle
Luteal phase A period ofcorpus luteum activity (days 14
28). After ovulation, the rupturedfollicle collapses, granulosa cells
enlarge, and along with internal
thecal cells, form the corpus
luteum The corpus luteum
secretes progesterone and
estrogen..
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Ovarian Cycle
Luteal phasecont.
If pregnancy does not occur, the
corpus luteum degenerates in 10
days, leaving a scar (corpus
albicans) in the ovary. If
pregnancy occurs, the corpus
luteum produces hormones until
the placenta takes over that role(at about 3 months of gestation)
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MENSTRUAL CYCLE
What actuallyhappens in
those 28 days?
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Uterine (Endometrial) Cycle
Monthly cyclical changes in the
endometrium of uterus for prepration
of implantation (in the event of
fertilization) and for menstruation (in
the absence of fertilization) is calleduterine cycle.
The uterine endometrial cycle can be
divided into three phases:
the proliferative phase,
the secretary,
the menstrual phase.
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Uterine (Endometrial) Cycle
Proliferative Phase
The proliferative or follicular, phase,spans from the end of themenstruation until ovulation.
Under the influence of increasinglevels of estrogen secreted byovarian follicles all elements ofendometrium proliferate.
The raw surface of endometrium is
again covered with epitheliumwhich proliferates out from theremains of the stems of uterineglands. The stromal cells increase
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Uterine (Endometrial) Cycle
Proliferative Phase cont.
Endometrial glands elongate with
cells containing some glycogen.But it is not secreted during the
follicular phase.
Spiral arteries supplying blood
also elongate. Stratum
functionalis thus resumed
again.
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Uterine (Endometrial) Cycle
Secretary Phase
The luteal, or secretory phase,
begins at ovulation and lasts until
the menstrual phase of the nextcycle.
At the beginning of the luteal
phase, progesterone induces the
endometrial glands to secreteglycogen, mucus, and other
substances. These glands become
tortuous and have large lumens
due to increased secretary activity.
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Uterine (Endometrial) Cycle
Secretary Phase cont.
The spiral arteries extend into the
superficial layer of the
endometrium.
In the absence of fertilization by
day 23 of the cycle, the corpus
luteum begins to degenerate and
consequently ovarian hormonelevels decrease.
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Uterine (Endometrial Cycle)
Secretary Phase cont.
As estrogen and progesterone
levels decrease, the
endometrium undergoes
involution.
Days 25-26 of the menstrual
cycle, endothelin and thromboxin
begin to mediate
vasoconstriction of the spiral
arteries. The resulting ischemia
may cause some early menstrual
cramps.
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Uterine (Endometrial Cycle)
Secretary Phase cont.
By day 28 of the
menstrual cycle, intense
vasoconstriction andsubsequent ischemia
cause mass apoptosis of
the stratum functionalis.
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Uterine (Endometrial) Cycle
Menstrual Phase
The menstrual phase begins as the
spiral arteries rupture secondary to
ischemia, releasing blood into the
uterus, and the apoptosed
endometrium is sloughed off. It
usually lasts four days. During this
period, the stratum functionalis is
completely shed.
Arterial and venous blood, remnants of
endometrial stroma and glands,
leukocytes, and red blood cells are all
present in the menstrual flow.
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Hormonal control
1. Pituitary gland release
Follicle Stimulating Hormone
(FSH) that acts on the ovary.
2. Ovarian follicles grow and
mature under influence of
FSH, and produce
increasing quantities of
estrogen
3. When levels of estrogenreach a threshold level, a
feed back process
decreases the production of
FSH by the pituitary.
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Hormonal control
4. Increased estrogen levels
trigger the release of
Luteinizing Hormone (LH) from
the pituitary gland
5. Ovulation occurs, that is
release of an egg from the
follicle.
6. The empty follicle forms the
corpus luteum, which produces
progesterone which maintains
the endometrium in a state of
readiness to receive a fertilized
egg
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Hormonal control
7. If the fertilized egg does
not implant itself the
progesterone level fallsand mensturation
commences.
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Summary of Reproductive
Hormones in Females
Hypothalamus releases Gonadotropin Releasing Hormone (GRH)
which binds with receptors in Ant. Pituitary
Anterior Pituitary releases Follicle Stimulating Hormone (FSH) and
Luteinizing Hormone(LH) pass in blood to site of action FSH acts on receptors in ovaries to stimulate development of the egg
follicles
LH causes rupture of egg follicles.
Rupture of egg triggers production ofestrogens and progestogens
from remaining tissues of follicle,corpus luteum
These hormones travel in blood to the brain
Hypothalamus senses levels, then may decrease release of GRH
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At end of this study you are able to
Describe structure of ovary, uterine tubesand uterus
Discuss the cyclic changes in the femalegenital tract, which include: The ovarian cycle (phases and hormonal
control). The uterine cycle (phases and hormonal
control)