OVARIAN AND UTERINE OVARIAN AND UTERINE CYCLESCYCLES

By: Dr. Mujahid KhanBy: Dr. Mujahid Khan

Female Reproductive CyclesFemale Reproductive Cycles

• Starts at pubertyStarts at puberty• Normally continues until the reproductive Normally continues until the reproductive

yearsyears• Sexual or reproductive cycle involves Sexual or reproductive cycle involves

activities of hypothalamus, pituitary gland, activities of hypothalamus, pituitary gland, ovaries, uterus, uterine tubes, vagina and ovaries, uterus, uterine tubes, vagina and mammary glandsmammary glands

GnRHGnRH• Gonadotropin-releasing hormone (GnRH) Gonadotropin-releasing hormone (GnRH)

is synthsized by neurosecretory cells in is synthsized by neurosecretory cells in the hypothalamusthe hypothalamus

• Carried to the anterior pituitary gland by Carried to the anterior pituitary gland by hypophysial portal systemhypophysial portal system

• Stimulates the release of 2 hormones Stimulates the release of 2 hormones produced by this gland that act on ovariesproduced by this gland that act on ovaries

FSHFSH

• Follicle-Stimulating Hormone stimulates Follicle-Stimulating Hormone stimulates the development of ovarian folliclesthe development of ovarian follicles

• Production of Estrogen by the follicular Production of Estrogen by the follicular cellscells

LHLH

• Luteinizing Hormone serves as the trigger Luteinizing Hormone serves as the trigger for ovulationfor ovulation

• Stimulates the follicular cells and corpus Stimulates the follicular cells and corpus luteum to produce progesteroneluteum to produce progesterone

OVARIAN CYCLEOVARIAN CYCLE

• FSH and LH produce cyclic changes in FSH and LH produce cyclic changes in ovaries called Ovarian Cycleovaries called Ovarian Cycle

• They cause development of follicles, They cause development of follicles, ovulation and corpus luteum formationovulation and corpus luteum formation

Follicular DevelopmentFollicular Development

• Growth and differentiation of primary Growth and differentiation of primary oocyteoocyte

• Proliferation of follicular cellsProliferation of follicular cells

• Formation of Zona PellucidaFormation of Zona Pellucida

• Development of the Theca FolliculiDevelopment of the Theca Folliculi

Theca FolliculiTheca Folliculi

• Formed as the primary follicle increases in Formed as the primary follicle increases in size and the adjacent connective tissue size and the adjacent connective tissue organizes into a capsuleorganizes into a capsule

• Theca Interna: Internal, vascular and Theca Interna: Internal, vascular and glandularglandular

• Theca Externa: A capsule like layerTheca Externa: A capsule like layer

AntrumAntrum

• Is a large fluid filled cavity appears around Is a large fluid filled cavity appears around the follicular cells of ovarian folliclethe follicular cells of ovarian follicle

• Contains follicular fluidContains follicular fluid

• Ovarian follicle now called a vesicular or Ovarian follicle now called a vesicular or secondary folliclesecondary follicle

Cumulus OophorusCumulus Oophorus

• The primary oocyte is pushed aside of the The primary oocyte is pushed aside of the follicle called Cumulus Oophorusfollicle called Cumulus Oophorus

• Here it is surrounded by a mound of Here it is surrounded by a mound of follicular cellsfollicular cells

• It projects into the antrumIt projects into the antrum

• The follicle becomes enlarge until it gets The follicle becomes enlarge until it gets maturitymaturity

• Produces swelling on the surface of the Produces swelling on the surface of the ovaryovary

• Early development of ovarian follicle is Early development of ovarian follicle is induced by FSHinduced by FSH

• Final stages of maturation require LHFinal stages of maturation require LH

EstrogenEstrogen

• Growing follicles produce estrogenGrowing follicles produce estrogen

• It regulates the development and functions It regulates the development and functions of reproductive organsof reproductive organs

• Vascular theca interna also produces Vascular theca interna also produces some estrogensome estrogen

OvulationOvulation• It occurs around mid cycle about 14 days It occurs around mid cycle about 14 days

in a 28 day menstrual cyclein a 28 day menstrual cycle

• Ovarian follicle undergoes sudden growth Ovarian follicle undergoes sudden growth spurt under the influence of FSH & LHspurt under the influence of FSH & LH

• Producing swelling or a bulge on Ovarian Producing swelling or a bulge on Ovarian surface surface

• An avascular spot appears on this swelling An avascular spot appears on this swelling called Stigmacalled Stigma

OvulationOvulation• Cumulus Oophorus detach from interior of the Cumulus Oophorus detach from interior of the

distended follicledistended follicle

• It is triggered by a surge of LH productionIt is triggered by a surge of LH production

• It usually follows the LH peak 12-24 hrsIt usually follows the LH peak 12-24 hrs

• LH Surge causes the stigma to balloon out LH Surge causes the stigma to balloon out forming a vesicleforming a vesicle

• The stigma ruptures and expel secondary oocyte The stigma ruptures and expel secondary oocyte with the follicular fluidwith the follicular fluid

OvulationOvulation• Expulsion of oocyte results from raised Expulsion of oocyte results from raised

intrafollicular pressureintrafollicular pressure

• The expelled secondary oocyte is The expelled secondary oocyte is surrounded by Zona Pellucida and layers surrounded by Zona Pellucida and layers of follicular cells called Corona Radiataof follicular cells called Corona Radiata

• Zona Pellucida is composed of 3 Zona Pellucida is composed of 3 glycoproteins ZPA, ZPB & ZPCglycoproteins ZPA, ZPB & ZPC

Corpus LuteumCorpus Luteum

• After ovulation the walls of the ovarian follicle After ovulation the walls of the ovarian follicle and theca folliculi collapse and thrown into and theca folliculi collapse and thrown into folds called Corpus folds called Corpus

LuteumLuteum

Corpus LuteumCorpus Luteum• It secretes Progesterone and some estrogenIt secretes Progesterone and some estrogen

• These hormones stimulate endometrial glands These hormones stimulate endometrial glands to secrete and prepare endometrium for to secrete and prepare endometrium for implantation of fertilized Ovum (Blastocyst)implantation of fertilized Ovum (Blastocyst)

• If the oocyte is fertilized the CL enlargesIf the oocyte is fertilized the CL enlarges

• If the oocyte is not fertilized the CL involutes If the oocyte is not fertilized the CL involutes and degenerates in 10-12 daysand degenerates in 10-12 days

Uterine or Menstrual CycleUterine or Menstrual Cycle

• It is the period during which the oocyte It is the period during which the oocyte matures, is ovulated and enters the uterine matures, is ovulated and enters the uterine tubetube

• Cyclic changes in the endometrium Cyclic changes in the endometrium caused by estrogen and progesteronecaused by estrogen and progesterone

• These changes occur in the internal layer These changes occur in the internal layer of the Uterusof the Uterus

Menstrual CycleMenstrual Cycle• Average menstrual cycle is 28 daysAverage menstrual cycle is 28 days

• Day 1 is the day when menstrual flow Day 1 is the day when menstrual flow beginsbegins

• It vary in length by several days in normal It vary in length by several days in normal womenwomen

• Ranges between 23 and 35 days in 90% Ranges between 23 and 35 days in 90% of womenof women

Phases of Menstrual CyclePhases of Menstrual Cycle

• Menstrual PhaseMenstrual Phase

• Proliferative PhaseProliferative Phase

• Luteal PhaseLuteal Phase

• Ischemic PhaseIschemic Phase

Menstrual PhaseMenstrual Phase

• Starts with 1Starts with 1stst day of menstrual cycle day of menstrual cycle

• Lasts for 4-5 daysLasts for 4-5 days

• Functional layer of uterine wall is sloughed Functional layer of uterine wall is sloughed off and discarded with the menstrual flowoff and discarded with the menstrual flow

• Blood discharge from vagina is combined Blood discharge from vagina is combined with small pieces of endometrial tissuewith small pieces of endometrial tissue

Proliferative PhaseProliferative Phase• Is a phase of repair and proliferationIs a phase of repair and proliferation

• Lasts for 9 daysLasts for 9 days

• Coincides with growth of ovarian follicleCoincides with growth of ovarian follicle

• Controlled by estrogen secreted by folliclesControlled by estrogen secreted by follicles

• 2-3 fold increase in thickness of endometrium2-3 fold increase in thickness of endometrium

• The glands increase in number and length and the The glands increase in number and length and the spiral arteries elongatespiral arteries elongate

Luteal PhaseLuteal Phase• Is a secretory or progesterone phaseIs a secretory or progesterone phase

• Lasting about 13 daysLasting about 13 days

• Coincides with formation, functioning and growth of Coincides with formation, functioning and growth of corpus luteumcorpus luteum

• Glandular epithelium secrete glycogen rich materialGlandular epithelium secrete glycogen rich material

• Endometrium thickens under the influence of estrogen Endometrium thickens under the influence of estrogen and progesteroneand progesterone

Luteal PhaseLuteal Phase

• Spiral arteries grow into the superficial Spiral arteries grow into the superficial layerlayer

• Arteries become increasingly coiledArteries become increasingly coiled

• Large venous network developsLarge venous network develops

• Direct arterio-venous anastomoses are the Direct arterio-venous anastomoses are the prominent featuresprominent features

If Fertilization OccursIf Fertilization Occurs

• Fertilized ovum implants in endometrium Fertilized ovum implants in endometrium on about 6on about 6thth day of this phase day of this phase

• HCG hormone secreted by HCG hormone secreted by syncytiotrophoblast keeps the corpus syncytiotrophoblast keeps the corpus luteum secreting estrogen and luteum secreting estrogen and progesteroneprogesterone

• The luteal phase continues and The luteal phase continues and menstruation does not occurmenstruation does not occur

If Fertilization Doesn’t OccurIf Fertilization Doesn’t Occur

• No HCGNo HCG

• Corpus luteum degeneratesCorpus luteum degenerates

• Estrogen and progesterone levels fallEstrogen and progesterone levels fall

• Secretory endometrium enters an ischemic Secretory endometrium enters an ischemic phasephase

• Menstruation occursMenstruation occurs

Ischemic PhaseIschemic Phase

• Decreased levels of estrogen & progesteroneDecreased levels of estrogen & progesterone• Stoppage of glandular secretionStoppage of glandular secretion• Loss of interstitial fluid Loss of interstitial fluid • Marked shrinking of endometriumMarked shrinking of endometrium• Spiral arteries become constrictedSpiral arteries become constricted• Venous stasis & Ischemic necrosisVenous stasis & Ischemic necrosis• Rupture of damaged vessel wallRupture of damaged vessel wall• Blood seeps into the surrounding connective Blood seeps into the surrounding connective

tissuestissues

Ischemic PhaseIschemic Phase• Pools of blood form and break through the Pools of blood form and break through the

endometrial surfaceendometrial surface

• Resulting in bleeding in uterine lumen and Resulting in bleeding in uterine lumen and from the vaginafrom the vagina

• Loss of 20-80 ml of bloodLoss of 20-80 ml of blood

• Entire compact layer and most of the Entire compact layer and most of the spongy layer of endometrium is discardedspongy layer of endometrium is discarded

Pregnancy PhasePregnancy Phase• If pregnancy occurs, endometrium passes If pregnancy occurs, endometrium passes

into the pregnancy phaseinto the pregnancy phase

• Menstruation cycle resumes 6-10 weeks Menstruation cycle resumes 6-10 weeks after the termination of pregnancyafter the termination of pregnancy

• Menopause usually occurs between the Menopause usually occurs between the ages of 48-55ages of 48-55

• Termination of reproductive period causes Termination of reproductive period causes psychic changes called Climactericpsychic changes called Climacteric

AnovulationAnovulation• Some women do not ovulateSome women do not ovulate• Inadequate release of gonadotropins (FSH Inadequate release of gonadotropins (FSH

& LH)& LH)• Ovulation can be induced by clomiphene Ovulation can be induced by clomiphene

citratecitrate• This stimulates pituitary to secrete This stimulates pituitary to secrete

gonadotropinsgonadotropins• Causes multiple ovulationCauses multiple ovulation• Multiple pregnanciesMultiple pregnancies• Spontaneous abortionsSpontaneous abortions