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What is ovulation?

Ovulation is the process that
happens usually once in every
menstrual cycle, when hormone
changes trigger an ovary to
release an egg
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SPONTANEOUS AND INDUCED
OVULATION
 Spontaneous ovulation occurs in lots of species (including humans) whose
females’ sexual cycles and release of eggs are affected only by their own
hormones
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Cyclic activity is
continually polyestrous or seasonal polyestrous
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Only one cycle per year, ovulate because
of mating
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OVULATION IN HUMANS
In humans, ovulation occurs about midway through the menstrual cycle, after the follicular phase and is
followed by luteal phase
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The time from the beginning of the last menstrual period
(LMP) until ovulation is, on average, 14
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Ovulation is characterized by a sharp spike in levels of LH
and FSH, resulting from the peak of estrogen levels during the follicular phase
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Granulosa cells converts androstenedione in to estradiol, a type of estrogen
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The building concentrations of LH & FSH marks the beginning of the preovulatory phase
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The ovum is supported by both the corona radiate & cumulus oophorus granulosa cells
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Mucification:
Secretion of a hyaluronic acid-rich cocktail lthat disperses & gathers the cumulus cell network in a
sticky matrix around the ovum
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 An increase in cumulus cell number causes an increase in antrum fluid volume that can swell the
follicle to over 20mm in diameter
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OVULATORY PHASE

 Proteolytic enzyme are secreted by the follicles, degrade the follicular tissue at the site of the
blister, forming a hole called the stigma
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 After entering the oviduct, the ovum-cumulus complex(COC) is pushed along by cilia,
beginning its journey toward the uterus
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 Meiosis II follows at once but will be arrested in the metaphase and will so remain until
fertilization
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 If no fertilization occurs, the oocyte will degenerate approximately 24 hours after ovulation
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LUTEAL PHASE (POST-OVULATORY
PHASE)
 During the luteal (post-ovulatory) phase, the secondary oocyte will travel
through the fallopian tubes toward the uterus
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 The follicle proper has met the end of its lifespan
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 These hormones induce the endometrial glands to begin production of
the proliferative endometrium and later into secretory endometrium, the site of
embryonic growth if implantation occurs
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The graph above shows the hormones that are involved in ovulation, and how
they must change throughout the cycle in order for ovulation to occur:

OVULATION PAIN

 Ovulation pain is also known as mid-cycle pain and mittelschmerz (German for
‘middle pain’)
...
The

duration of the pain varies from one woman to the next, but ranges from a few
minutes to 48 hours
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MECHANISM OF OVULATION
1
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2
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• Increased in prostaglandins
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– Plasmin is an enzyme produced in the body for breaking down fibrin, a key component
in blood clots
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It weakens the wall of the Graafian
follicle (leading to ovulation)
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Neuromuscular mechanisms
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Prostaglandins cause contraction of the ovary and walls of follicle and contribute to rupture
and expulsion of oocyte
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• Follicles rupture contents into peritoneal cavity
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