Transcript Female Hormonal Cycle - also known as the MENSTRUAL CYCLE

IN THE NAME OF GOD
Female Horonal Cycle
MENSTRUAL CYCLE
E.Naghshineh MD
Reproductive hormons:
GnRH
• 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
• LH &FSH: by ant pituitary gonadotroph
cells
• Ovarian follicular stimulation
• Glycoproteins, alpha &beta subunit
Prolactin
• 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
• 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
• 9 aa peptide, by paraventricular nucleus
of hypothalamus
• Uterine muscular contraction, breast
lactiferous duct myoepithelial
contraction
MENSTRUAL CYCLE
• Normal cycle length is considered 28 days
• varies from female to female (21-35 days)
• Ovarian cycle: 1-follicular ,2-luteal
• Uterine cycle: 1-proliferative ,2-secreatory
1 – Follicular phase
• Development dominant follicle, mature
at midcycle, ovulation
• Average length:10-14 days
• Variability in length: variations in total
cycle length
2-luteal phase
• Ovulation to menses
• Average length: 14 days
Normal menstrual cycle
• 21-35 days
• 2-6 days of flow
• Average blood loss:20-60 ml
Hormonal variations
1. At the beginning of cycle: levels of
gonadal steroids are low
2. Demise of corpus luteum, FSH levels
rise, cohort of growing follicles is
recruited, rise in estrogen: stimulus
for uterine endometrial proliferation
3. 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
4.At the end of follicular phase (just
before ovulation) FSH-induced LH
receptors on granulosa cells;
with LH stimulation, modulate secretion
of progesterone
7.Progesteron levels rise after ovulation;
presumptive sign of ovulation
8.Progesteron;estrogen and inhibin-A :
suppress gonadotropin secretion and
new follicular growth
5.After sufficient degree of estrogenic
stimulation; pituitary LH surge triggered,
proximate cause of ovulation occurs
24 to 36 hours later
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
Cyclic changes of the Endometrium
• Decidua functionalis: 2/3 superficial,
proliferate and shed each cycle
• Decidua basalis: deepest region,
source of endometrial regeneration
after each menses
1-Proliferative phase
• 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
• 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 days before menses:dramatic
increases in PMN migrate from vascular
system
Menses
• 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
• Oogonia: only one final daughter cell
(oocyte), three polar body
• Oocyte arrested in prophase (diploten)
until time of ovulation
Two-cell two-gonadotropin theory:
with LH stimulation, the ovarian theca
cells produce androgens that convert
by granulosa cells into estrogens
under the stimulus of FSH
THE END