Transcript Female Hormonal Cycle - also known as the MENSTRUAL CYCLE

Female Hormonal Cycle
MENSTRUAL CYCLE
by : S. Rouholamin MD
Reproductive hormones: GnRH
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GnRH: decapeptide, by neurons in arcuate
nucleus of hypothalamus
Regulate secretion of two hormones: FSH
and LH
Pulsatile secretion
Extremely short half-life: only 2-4 min
Gonodotropins
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LH &FSH: by ant pituitary gonadotroph
cells
Ovarian follicular stimulation
Glycoproteins, alpha &beta subunit
Prolactin
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Poly peptide, by ant pituitary lactotroph
Primary trophic factor responsible for
the synthesis of milk by breast
PRL secretion is under tonic inhibitory
control by hypothalamic secretion of
dopamine
PRL stimulation: breast manipulation,
drugs, stress, exercise, certain foods
TSH
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By ant pituitary thyrotrophs in response
to TRH
TRH:by arcuate nucleus ,portal
circulation, pituitary
TRH: TSH & PRL release
Hypo- and hyperthyroidism: ovulatory
dysfunction
Oxytocin
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9 aa peptide, by paraventricular nucleus
of hypothalamus
Uterine muscular contraction, breast
lactiferous duct myoepithelial
contraction
MENSTRUAL CYCLE
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Normal cycle length is considered 28 days
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varies from female to female (21-35 days)
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Ovarian cycle: 1-follicular ,2-luteal
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Uterine cycle: 1-proliferative ,2-secreatory
1 – Follicular phase
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Development dominant follicle, mature
at midcycle, ovulation
Average length:10-14 days
Variability in length: variations in total
cycle length
2-luteal phase
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Ovulation to menses
Average length: 14 days
Normal menstrual cycle
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21-35 days
2-6 days of flow
Average blood loss:20-60 ml
Hormonal variations
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At the beginning of cycle: levels of
gonadal steroids are low
Demise of corpus luteum, FSH levels
rise, cohort of growing follicles is
recruited, rise in estrogen: stimulus
for uterine endometrial proliferation
Hormonal variations
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Rising estrogen levels: negative feedback
on pituitary FSH secretion;
growing follicle produce inhibin-B:
suppresses pituitary FSH secretion;
Rising estrogen levels: LH initially
decreases
but late in follicular phase LH levels
increased dramatically
Hormonal variations
4.
At the end of follicular phase (just
before ovulation) FSH-induced LH
receptors on granulosa cells;
with LH stimulation, modulate
secretion of progesterone
Hormonal variations
5.
After sufficient degree of estrogenic
stimulation; pituitary LH surge
triggered, proximate cause of
ovulation occurs 24 to 36 hours
later
Hormonal variations
6.
Estrogen level decreases through
the early luteal phase from just
before ovulation until midluteal
phase, rise again as a result of
corpus luteum secretion
Hormonal variations
7.
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Progesteron levels rise after
ovulation; presumptive sign of
ovulation
Progesteron;estrogen and
inhibin-A : suppress
gonadotropin secretion and new
follicular growth
Cyclic changes of the
Endometrium
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Decidua functionalis: 2/3 superficial,
proliferate and shed each cycle
Decidua basalis: deepest region,
source of endometrial regeneration
after each menses
1-Proliferative phase
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First day of vaginal bleeding :day 1 of
the menstrual cycle
Progressive mitotic growth of decidua
functionalis, preparation for implantation
of embryo
Thin endometrium (1-2 mm); straight,
narrow, short endometrial glands
become longer, tortuous structures
2-Secretory phase
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48 to 72 hours following ovulation,
progesteron secretion: eosinophilic
protein-rich secretory product in glandular
lumen
Postovulatory day 6-7,maximal secretory
activity: optimal for implantation of
blastocyst
Stromal edema in late secretory phase
2-Secretory phase
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2 days before menses:dramatic
increases in PMN migrate from
vascular system
Menses
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Absence of implantations, glandular
secretion ceases, irregular break-down of
decidua fuctionalis
Destruction of corpus luteum and its
productions estrogen and progesteron:
cause of shedding
Withdrawal of sex steroids: spiral art
spasm, endometrial ischemia, lysosoms
breakdown, proteolytic enzymes release
Ovarian follicular development
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Fetus:6-7 million in 20 wks
At birth:1-2 million
At puberty:300,000
Release during ovulation:400-500
At menopause:rare
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Oogonia: only one final daughter
cell (oocyte), three polar body
Oocyte arrested in prophase
(diploten) until time of ovulation
Two-cell two-gonadotropin
theory
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with LH stimulation, the ovarian
theca cells produce androgens
that convert by granulosa cells
into estrogens under the
stimulus of FSH