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Menstrual CycleThe recurring monthly series of physiological changes in female primates in which an egg is produced in the process known as ovulation, and the uterine lining thickens to allow for implantation if fertilization occurs. If the egg is not fertilized, the lining of the uterus breaks down and is discharged during menstruation.

Menstrual CycleIn 7th-8th month of intrauterine life ----- 6 million primordial follicles in single ovary

At the time of birth ---- only 1 million primordial follicles in both ovaries and the rest degenerates

At puberty ---- the number of total promordial follicles get reduced to 300,000 40,000

Menstrual CycleDuring menstrual cycle One primordial follicle is matured into graafian follicle and ovum and is released by one of the ovaries (about 450 primordial follicle in females reproductive life)

Many primordial follicle degenerates

Degeneration of follicle is known as atresia and resulting degenerated follicle is known as atresic follicle

Menstrual CyclePuberty (12-15 years)MenarcheMenopause (40-45 years)

Duration: Start of menstruation bleeding till the start of next menstruation bleeding20-40 daysUsually 28 days

Changes during menstrual cycleOvarian changesUterine changesVaginal changesCervical changes

Menstrual cycle : Ovarian changes2 phasesFollicular phase Luteal phase

Menstrual cycle : Ovarian changes

Menstrual cycle : Ovarian changesFollicular phase 5th day 14th day of cycleAt each stage ovum is surrounded by granulosa cellsOvum and its surrounding granulosa cells make follicleMaturation of ovum with corresponding development of folliclePrimordial follicle primary follicle Vesicular follicle Graafian follicle or mature follicleMenstrual cycle : Ovarian changesOvulation: rupture of graafian follicle and release of ovum into abdominal cavity

Enters fallopian tubeUsually on 14th day in normal 28 days cycleRemain viable for 24-48 hrsSurge of LH is necessary for ovulation

Menstrual cycle : Ovarian changesLuteal phase15th day 28th dayDevelopment of corpus luteumYellow body

Menstrual cycle : Ovarian changesLuteal phase Function of Corpus LuteumTemporary endocrine organLH influence CL to secretelarge amounts of progesteronesmall amount of estrogen

Maintenance of pregnancy

Menstrual cycle : Ovarian changesLuteal phase Fate of Corpus LuteumIf the ovum is not fertilizedCL reaches maximum size after one week of ovulation and secrete large quantity of progesterone and small quantity of estrogen

After one week of ovulation CL undergo luteolysisStructure and functional regression and degenerationCL become smaller and cells decrease in size and then later into white scar (corpus albicans)

Menstrual cycle : Ovarian changesLuteal phase Fate of Corpus LuteumIf the ovum is fertilized and pregnancy occurs CL increase in size and persist for 3-4 months (corpus luteum of pregnancy) First trimester----secrete large quantities of progesterone and small quantities of estrogen ------ maintenance of pregnancyAfter 3-4 months, placenta take over and CL degeneratesAbortion occurs if CL become inactive or is removed before three months of pregnancy

Menstrual cycle : Uterine changesSimultaneous changes in ovary and uterus3 phasesMenstrual phaseProliferative phaseSecretory phase

Menstrual cycle : Uterine changesProliferative phase 5th 14th day of cycleMenstruation stops ovulationCorresponds to the follicular phase of ovarian cycleAfter menses thin layer of endometrium remainsProliferative phase: rapid proliferation of endometrium, blood vessel and development of glandsLH induces the ovulation on 14th day

Menstrual cycle : Uterine changesSecretory phase 15th 28th day of cycleOvulation start of next cycleDevelopment of corpus luteumSecrete estrogen and progesterone to prepare uterus for implantation of fertilized ovum (pregnancy)increase in the thickness of endometriumdevelopment of glands development of new blood vessel and increase blood supply Deposition of fats and glycogen

Menstrual cycle : Uterine changesSecretory phase

If pregnancy does not occur ----- menstrual phaseIf pregnancy occur ----- changes in uterus for the development and survival of fetus

Menstrual cycle : Uterine changesMenstural phase If the pregnancy occur then thickened endometrium (uterine lining) persists

If pregnancy does not occur then menstrual phase or period occurs (aka menses, menstruation)Thickened endometrium (uterine lining) is shed and expelled through vagina with some blood and tissue fluid

It lasts 4-5 days

Menstrual cycle : Uterine changesMenstural phase During the last two days of secretory phase, secretion of large quantities of estrogen and progesterone inhibits secretion of FSH and LH from anterior pituitary.

Without FSH and LH corpus luteum become inactive and start degenerating

As a result there is a sudden decline in amount of progesterone and estrogen

So thickened endometrium cannot be maintained and menstrual bleeding ensues

Regulation of menstural cycleComplex processHormones involved are:Hypothalmic hormones ----- GnRH (gondaotropin releasing hormone)Anterior pituatry hormones ----- LH, FSHOvarian hormones ------ estrogen, progesterone

Menstrual cycle : Control

External factors, feedback from ovarian hormonesrecruitment and development of immature ovarian folliclesovulation, sustains corpus luteum by CL, by ovarian folliclesEstrogen: by Ovarian follicles, by CLDisorders of menstrual cycleAmenorrhea

Hypomenorrhea

Menorrhagia

Oligomenorrhia

Polymenorrhea

Dysmenorrhea

Metorrhagia

Disorders of menstrual cycleDysmenorrhea or Menstual CrampsOccurs during regular ovulatory cycles. Destruction of the endometrial cells and the resultant release of their contents ----- Prostaglandins are released during menstruation due to Women with primary dysmenorrhoea have increased activity of the uterine muscle with increased contractility and increased frequency of contractions.Drugs which inhibit the production of prostaglandins, such as the non-steroidal anti-inflammatory drugs (NSAIDs) Naproxen, Ibuprofen and Mefenamic Acid, can provide relief for the discomfort and other associated symptoms of excessive prostaglandin release, such as nausea, vomiting, and headache.

Disorders of menstrual cycleDysmenorrhea or Menstural Cramps

Anovulatory cyclesIt is the menstrual cycle in which ovulation does not occur

Menstrual bleeding occurs

It is common during puberty and few years before menopause (perimenopause)

If occurs in reproductive life of female then leads to infertility

Anovulatory cyclesThere are variety of underlying causes for anovulatory cycles in female reproductive life

Hormonal balanceProlonged strenuous exercise programEating disorderHypothalamic dysfunctionsTumors in pituitary, ovary or adrenal glandsLong term use of certain drugs like steroidal contraceptive

MenopausePermanent stoppage of menstrual cycleDecrease in secretion of sex hormones (estrogen and progesterone)Age 45-55 years

ReasonsNatural Gradual atrophy of ovariesLess estrogen and progesteroneSurgical (ovariectomy, hysterectomy)