1.Conception

8/8/2019 1.Conception

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CONCEPTIONCONCEPTION



CONCEPTUSCONCEPTUS

Cells and membranes resulting fromCells and membranes resulting fromfertilization of the ovum at any stage of fertilization of the ovum at any stage of

prenatal development.prenatal development.



CORPUS LUTEUMCORPUS LUTEUM

Graffian follicle cells remaining afterGraffian follicle cells remaining afterovulation. These cells produce estrogen andovulation. These cells produce estrogen and

progesterone.progesterone.



EJACULATIONEJACULATION

Expulsion of semen from the penis.Expulsion of semen from the penis.



EMBRYOEMBRYO

The developing baby from theThe developing baby from thebeginning of the third week through thebeginning of the third week through the

eighth week after conception.eighth week after conception.



ENDOMETRIUMENDOMETRIUM

Lining of the uterus.Lining of the uterus.



F ERTILIZATION AGEF ERTILIZATION AGE

Prenatal age of the developing baby,Prenatal age of the developing baby,calculated from the date of conception. Alsocalculated from the date of conception. Also

called post conceptional age.called post conceptional age.



F ETUSF ETUS

The developing baby from 9 weeksThe developing baby from 9 weeksafter conception until birth. In everydayafter conception until birth. In everyday

practice, this term is of ten used to describepractice, this term is of ten used to describea developing baby during pregnancy,a developing baby during pregnancy,regardless of age.regardless of age.



GAMETEGAMETE

Reproductive cell: in the female anReproductive cell: in the female anovum, and in the male a spermatozoon.ovum, and in the male a spermatozoon.



GESTATIONAL AGEGESTATIONAL AGE

Prenatal age of the developing babyPrenatal age of the developing baby(measured in weeks) calculated from the(measured in weeks) calculated from the

first day of the woman s last menstrualfirst day of the woman s last menstrualperiod. Also called menstrual age, about 2period. Also called menstrual age, about 2weeks longer than the fertilization age.weeks longer than the fertilization age.



GRAAF IAN F OLLICLEGRAAF IAN F OLLICLE

A small sac within the ovary. The A small sac within the ovary. Thegraafian follicle contains the maturing ovum.graafian follicle contains the maturing ovum.



NIDATIONNIDATION

Implantation of the fertilized ovumImplantation of the fertilized ovum(Zygote) in the uterine endomertrium.(Zygote) in the uterine endomertrium.



OOGENESISOOGENESIS

Formation of gametes (ova) in theFormation of gametes (ova) in thefemale.female.



OVULATIONOVULATION

Release of the mature ovum from theRelease of the mature ovum from theovary.ovary.



PLACENTAPLACENTA

Fetal structure that providesFetal structure that providesnourishment, removes wastes from thenourishment, removes wastes from thedeveloping baby, and secrete hormonesdeveloping baby, and secrete hormonesnecessary for the pregnancy to continue.necessary for the pregnancy to continue.



SPERMATOGENESISSPERMATOGENESIS

Formation of male gametes, or germFormation of male gametes, or germcells.cells.



ZYGOTEZYGOTE

Cell formed by union of an ovum andCell formed by union of an ovum andsperm.sperm.



CONCEPTIONCONCEPTION

Conception requires correct timing betweenrelease of a mature ovum at ovulation andenough healthy, mature , motile sperm into thevagina.

-Exact viability is unknown

-Ovum not > 24 Hrs and Sperm also-But some remain fertile up to 72 Hrs



ConceptionConception

A. Conception in Female

B. Conception in Male



A. Conception in Female1 .Preparation for conception in the female

2. Release of the ovum

3.Ovum Transport



A. Conception in Female



1 . Preparation for conception in1 . Preparation for conception inthe femalethe female

Hypothalamus

Releasing Gonadotrophin releasing hormone

Anterior Pituitary

Secretes FSH &LH

contd«



Several Oocytes begin to mature in Ovary-containing sac-³Graffian follicle´

Produces Estrogen and Progesterone

Prepares Endometrium for possiblePregnancy

- Eventually one follicle outgrows others.- The less mature Oocytes permanently

regress.



2 .2 .RELEASE OF THE OVUMRELEASE OF THE OVUM

The follicle develops a weak spot on theThe follicle develops a weak spot on thesurface of the ovarysurface of the ovary

It RupturesIt RupturesMatured ovum releasedMatured ovum released- -ovulationovulation

Collapsed follicle becomes CorpusluteumCollapsed follicle becomes Corpusluteumcondt«condt«



Maintains high Estrogen & ProgesteroneMaintains high Estrogen & Progesterone

Makes final preparation for receivingMakes final preparation for receiving

fertilized ovumfertilized ovum

Ovulation occurs about 1 4 days before aOvulation occurs about 1 4 days before a

women¶s next menstrual cyclewomen¶s next menstrual cycle



3 .Ovum Transport

Ovum released in abdominal Cavity

Picked up by the fimbriated ends of Fallopian tube

Transported through the tube by muscular actionand movement of cilia

contd«



Comes to Ampulla of Fallopian Tube(Distal 3 rd of the tube)

- The ovum fertilized or not, it enters the uterus

about 3 days after it release from the ovary



B . Conception in Male



B. Conception in Male1 .Preparation for conception in the Male

2.Ejaculation

3.Movement of the sperm in Femalereproductive Tract

4.Preparation of the sperm for actualFertilization



1 . Preparation for conception in themale

Hypothalamus

Luteinising hormone releasing hormone(LhRh)(GnRh)

Anteroir pituitarycontd«



Luteinising Hormone and Follicular StimulatingHormone (LH and FSH)

LH or Interstitial Cell Stimulating Hormone(ICSH) ± stimulates interstitial cells of the testisto secrete hormone TESTOSTERONEFSH ± stimulates production of male gametes



2. Ejaculation

At sexual Intercourse

200-600 million sperm deposited in upper vagina andover the cervix

The sperms are suspended in seminal fluid

It Nourishes and protects them from acidicvaginal medium



- The seminal fluid coagulates slightly after ejaculation to hold the semen deeply in vagina

- The sperm becomes immobile for 15 -30 mts- Other seminal enzyme dissolve the coagulated

fluid

- The sperm begin to move upward throughcervix



3.Movement of the sperm in Femalereproductive Tract

Whip like movement of the tails of the sperm

Propels them through cervix

Uterus

Fallopian Tubescontd«



Prostaglandins in seminal Fluid

Induce uterine contractions

Movement of sperm toward the ovum

- Only sperm cells enter the cervix

- Seminal fluid remains in the vaginacontd «



Many Sperms are last along the way.Some digested by vaginal enzymes and

phagocytes in the Female Reproductive Tract.

Others simply lose their way like to wrongtube, past the ovum, out into the peritonealCavity.

Only few hundreds reach the Fallopian Tubewhere the ovum is Located.



4. Preparation of the sperm for actualFertilization

After ejaculation

Sperms are not ready for fertilizing ovum

Sperm undergo changes while making trip to ovum

contd«.



Called- Capacitation( enable one sperm to penetrate protective layers of ovum)

-During Capacitation a glycoprotein coat and seminal proteins are removed from acrosome

After that- Sperm look the same but more active and can better

penetrate the coronaradiata andzonapellucida

contd«



Sperm that reach the ovum

Release an Enzyme-Hyaluranidase

It digest the pathway through coronaradiata and

zonapellucida

The tail beat harder to propel them toward center of ovum

So, one sperm penetrates ovum



Conception includes

A. FertilizationB. Pre-Embryonic periodC. Embryonic periodD.Fetal period



A.Fertilization

Fertilization occurs when one sperm entersthe ovum and the two nuclei containing the

parents¶ chromosomes mergei) Entry of one spermatozoon into the ovumii) Fusion of the Nuclei of sperm and ovum



i) Entry of one spermatozoon intothe ovum

i) - It has two resultsChanges in zonapellucida prevent other

sperm entryOvum Meiotic division discontinued inthe middle just before ovulation

completes meiosis.



ii) Fusion of the Nuclei of sperm andii) Fusion of the Nuclei of sperm andovumovum

--This begins when the sperm enters the ovumThis begins when the sperm enters the ovum

--Sperm head enlarges and the tail degeneratesSperm head enlarges and the tail degenerates

--Gametes nuclei move to center of the ovumGametes nuclei move to center of the ovum

Membranes surrounding them touch andMembranes surrounding them touch anddissolvedissolve

contd«contd«



The 23 chromosomes from the sperm mingleThe 23 chromosomes from the sperm minglewith 23 from the ovumwith 23 from the ovum

Restoring the diploid Number to 46Restoring the diploid Number to 46

-- Fertilization is complete, and cell divisionFertilization is complete, and cell divisioncan begin when nuclei of the sperm and ovumcan begin when nuclei of the sperm and ovumuniteunite



B.PreB.Pre--Embryonic PeriodEmbryonic Period

The PreThe Pre--Embryonic Period is the First 2 weeksEmbryonic Period is the First 2 weeksafter conceptionafter conceptionIt consist of It consist of

1 .Initiation of cell division1 .Initiation of cell division2.Entry of the zygote into the uterus2.Entry of the zygote into the uterus3.Implantation in the decidua3.Implantation in the decidua

4.Maintaining the decidua4.Maintaining the decidua5 .Location and Implantation5 .Location and Implantation6.Mechanism of Implantation6.Mechanism of Implantation



1 .Initiation of cell division1 .Initiation of cell division

The Zygote divides into 2, 4, 8, 1 6 cells while inThe Zygote divides into 2, 4, 8, 1 6 cells while inthe Fallopian tubethe Fallopian tube

Up to1

6Up to1

6--cell stage, cells become smaller with eachcell stage, cells become smaller with eachdivision, so they occupy the space same as ovumdivision, so they occupy the space same as ovum

When the conceptus is a solid ball of 1 2When the conceptus is a solid ball of 1 2--1 6 cells1 6 cells--MorullaMorulla

contd«contd«



Fluid filled cavityFluid filled cavity- -BlastoceleBlastocele

BlastocystBlastocyst--outer single layer of Trophoblastic andouter single layer of Trophoblastic andinner cellmass placed in center inner cellmass placed in center

Trophoblast & Inner cell massTrophoblast & Inner cell mass

PLACENTAPLACENTA FETUSFETUSAMNION CHORIONAMNION CHORION

UMBILICAL CORDUMBILICAL CORD



2.Entry of the zygote into the uterus2.Entry of the zygote into the uterus

* * Conceptus enters the uterus after 3 days of Conceptus enters the uterus after 3 days of conceptionconception--contains 1 00 cellscontains 1 00 cells

It Lingers in the uterus another 2It Lingers in the uterus another 2- -4 days before4 days beforeimplantation.implantation.

contd«contd«



* * EndometriumEndometrium- -DeciduaDecidua

In secretary phaseIn secretary phase

Endometrial glands are secreting maximum richEndometrial glands are secreting maximum richfluids to nourish conceptusfluids to nourish conceptus

--Endometrial spiral arteries are well developed inEndometrial spiral arteries are well developed insecretary phase, providing easy access for secretary phase, providing easy access for developing the placental blood supplydeveloping the placental blood supply



3.Implantation in the decidua3.Implantation in the decidua

-- Conceptus carries small supply of nutrients for Conceptus carries small supply of nutrients for early cell divisionearly cell division

-- Nucleation at proper time and Location in the uterus Nucleation at proper time and Location in the uterus

is crucial for continued developmentis crucial for continued development-- Implantation is gradual process that occurs betweenImplantation is gradual process that occurs between

66thth --1 01 0thth days.days.-- Embryonic structures also developingEmbryonic structures also developing



4.Maintaining the decidua4.Maintaining the decidua

Implantation and survival of the conceptusImplantation and survival of the conceptusDepends onDepends on

Continuous supply Estrogen and progesteroneContinuous supply Estrogen and progesterone

To maintain deciduaTo maintain decidua

Contd«Contd«



* * The zygoteThe zygoteSecretesSecretes

HCG Corpusluteum E and PHCG Corpusluteum E and P

Signal for pregnancy has begunSignal for pregnancy has begun



5 .Location of Implantation5 .Location of Implantation

Conceptus must be in right place at right timeConceptus must be in right place at right time

Normal implantation Normal implantation

-- Site of Implantation is important because that is theSite of Implantation is important because that is the place placenta develops place placenta develops

-- Normally It occurs in upper uterus (Fundus) Normally It occurs in upper uterus (Fundus)

contd«contd«



Fundus is the best area for implantation forFundus is the best area for implantation for3 reasons3 reasons1 )1 ) Rich blood supply for gas exchange and nutritionRich blood supply for gas exchange and nutrition

2)2) Uterus lining is thick Uterus lining is thick 3)3) Limits blood loss after birthLimits blood loss after birth



D ecidua BasalisD ecidua Basalis -- The portion directly under The portion directly under the blastocystthe blastocyst - - where the chorionic villi tapwhere the chorionic villi tapthe maternal blood vessels.the maternal blood vessels.

D ecidua CapsularisD ecidua Capsularis ± ± The portion coveringThe portion covering

the blastocyst.the blastocyst.D ecidua veraD ecidua vera ± ± The portion lining the rest of The portion lining the rest of the uterusthe uterus



C. Embryonic PeriodC. Embryonic Period

Beginning of 3Beginning of 3 rdrd week through 8week through 8 thth week after week after conceptionconceptionBasic structures of all major body organs areBasic structures of all major body organs arecompleted during embryonic periodcompleted during embryonic period



-- Differentiation of CellsDifferentiation of Cells

End of 8End of 8 thth week all organ systems are in place,week all organ systems are in place,Many functioning in a simple way.Many functioning in a simple way.Development of the specialized structures isDevelopment of the specialized structures iscontrolled by three factorscontrolled by three factors1 . Genetic information in the Chromosome1 . Genetic information in the Chromosome2. Interaction between adjacent tissues2. Interaction between adjacent tissues3. Timing3. Timing

contd«contd«



Structures are vulnerable to damage fromStructures are vulnerable to damage from

terotogensterotogensDevelopment of one structure makes normal andDevelopment of one structure makes normal and

proper development of another proper development of another

Earlier stage of pregnancy may not realized byEarlier stage of pregnancy may not realized bymother so make aware of drugs, Diagnosticmother so make aware of drugs, Diagnostic

procedures etc. procedures etc.



Weekly DevelopmentsWeekly Developments

Development of the Embryo and FetusDevelopment of the Embryo and Fetus* Cephalo caudal direction* Cephalo caudal direction* Central to peripheral direction* Central to peripheral direction

22ndnd Week Week * Implantation completed by end of 2* Implantation completed by end of 2 ndnd Wk Wk

*Trophoblast grows fastly*Trophoblast grows fastly*Inner mass becomes flattened into*Inner mass becomes flattened into

embryonic disk embryonic disk

33rdrd W kW k



33rdrd Week Week

11 stst

menstrual cycle missedmenstrual cycle missed

Embryonic disc develops 3 layersEmbryonic disc develops 3 layers

a.Ecto derma.Ecto derm b.Endo derm b.Endo dermc.Meso dermc.Meso derm

contd«contd«



Derivatives of the three germ layersDerivatives of the three germ layers

Ecto dermEcto derm--Brain and spinal cordBrain and spinal cord--Peripheral Nervous systemPeripheral Nervous system--Pituitary glandPituitary gland--Sensory Epithelium of the eye, ear andSensory Epithelium of the eye, ear andnosenose

--Epidermis, Hair & NailsEpidermis, Hair & Nails--Subcutaneous & Mammary glandsSubcutaneous & Mammary glands--Tooth enamelTooth enamel



Meso DermMeso Derm-- CartilageCartilage

--Bone, Connective tissue, Muscle tissueBone, Connective tissue, Muscle tissue

--Heart, Blood vessels, Blood cells, LymphaticHeart, Blood vessels, Blood cells, Lymphatic

system,system,

--Spleen, kidneys, Adrenal cortexSpleen, kidneys, Adrenal cortex

--Ovaries, Testes and Reproductive system liningOvaries, Testes and Reproductive system liningmembranesmembranes



Endo DermEndo Derm

-- Lining of G.I and Respiratory tractsLining of G.I and Respiratory tracts-- Tonsils and ThyroidTonsils and Thyroid-- Parathyroid, ThymusParathyroid, Thymus

-- Liver Liver -- PancreasPancreas-- Lining of urinary bladder and urethraLining of urinary bladder and urethra

-- Lining of Ear canalLining of Ear canal

contd«contd«



CNS begins developing 3CNS begins developing 3 rdrd week week

Thickened flat neural plate appears, extendsThickened flat neural plate appears, extendstoward end of Embryonic disk toward end of Embryonic disk- - becomes Head becomes Head

Heart develops as a pair of parallel tubes andHeart develops as a pair of parallel tubes and joins together joins together

Primitive heart begins beating at 2 1Primitive heart begins beating at 2 1 --22 days22 days

Primitive blood cells arise from the endo dermPrimitive blood cells arise from the endo dermlining the distal blood vesselslining the distal blood vessels



Fourth Week

The shape of the Embryo changesIt folds at the Head and Tail end and laterally.Remains in C- shape

Tail is apparent because brain and spinal corddevelop more rapidly than other systems

Neural tube closed by 4 th week. If not

Anencephaly and Spinabifida resultscontd«



4 WEEKS



Formation of Face and U.R.T beginsBeginnings of internal ear and Eye apparentUpper extremities appear as buds on the lateral

body walls

Heart partition into four chambers completed by6th week

contd«



L.R.T begins as a branch of upper digestivetract

Esophagus and trachea separate completelyTrachea branches to right and left bronchi &Then forms Lobs, Alveoli rich capillary

network that allows o2 &Co2 at birth



Fifth Week Fifth Week

Head is very large because the brain growsHead is very large because the brain growsrapidlyrapidly

Heart is beating and developing 4 chambersHeart is beating and developing 4 chambers

Upper limb buds are paddle shaped with obviousUpper limb buds are paddle shaped with obviousnotches of fingersnotches of fingers

Lower limbs are paddle shaped but area betweenLower limbs are paddle shaped but area betweenthe toes is not well definedthe toes is not well defined



Sixth Week Sixth Week Prominent Head due to rapid development andProminent Head due to rapid development and

is bent over the chestis bent over the chestHeart reaches its final 4 chambered formHeart reaches its final 4 chambered formUpper & Lower extremities become moreUpper & Lower extremities become moredefineddefinedEye continues to develop, External ear isEye continues to develop, External ear isapparent as 6 small bumps near each side of apparent as 6 small bumps near each side of

neck neck Facial development with eyes ,ears & nasal pits (Facial development with eyes ,ears & nasal pits (widely seperated )widely seperated )



Seventh Week Seventh Week Growth in all systems & refinement occursGrowth in all systems & refinement occurs

Face becomes more human lookingFace becomes more human looking

Eye lids begin to grow, Extremities longer &Eye lids begin to grow, Extremities longer & better defined better defined

Trunk elongates & straightens, CTrunk elongates & straightens, C- -shaped spinalshaped spinalcurve present still birthcurve present still birth

contd«contd«



Intestines grows faster than abdominal cavityIntestines grows faster than abdominal cavity

Large liver & kidney occupies more spaceLarge liver & kidney occupies more space

Umbilical cord contains most of the intestinesUmbilical cord contains most of the intestines

At 1 0At 1 0thth week abdomen is large to contain all itsweek abdomen is large to contain all its

contentscontents

Eighth WeekEighth Week



Eighth Week Eighth Week

Definite human form & refinement of allDefinite human form & refinement of allsystems continuesystems continue

LowLow--set ears but approaching their final locationset ears but approaching their final location

Eyes are pigmented , not fully covered byEyes are pigmented , not fully covered byeyelidseyelids

Fingers & Toes are stubby but well definedFingers & Toes are stubby but well defined

External genitalia begin to differentiate but MaleExternal genitalia begin to differentiate but MaleFemale characteristics are not distinctFemale characteristics are not distinct



8 WEEKS8 WEEKS



D.Fetal Period

9 weeks after conception & ends with birth

Dramatic growth and refinement in the structure &function of all organ systems

Less likely teratogen may damage already formedstructures

CNS is vulnerable for damage throughout pregnancy

W k 9 1 2



Weeks 9 - 1 2Head is large ie half of the total length of the fetusBody grows fast than headFinal relative length of extremities but leg remainshorter than arms

First fetal movements begin but too slightFace is broad, wide nose & Widely spaced eyesEyes closes at 9 weeks & reopen at about 26 weekscontd«



12 WEEKS



Low-set ears because Mandible is still small

Abdominal capacity increases intestinal contents entersin to it

At 9 th wk blood formation in liver that shifts to spleen by end of 1 2th wk

Urine produced & excrete into Amniotic fluidcontd...



Male & Female internal differences apparent in 7 th

week

External genitalia looks similar until end of 9 th

week

At 1 2th wk fetal sex can be determined by externalgenitalia appearance



Week 1 3 - 1 6

Rapid growth in length, so head becomes smaller in proportion to the total length

Strengthened Quickening mother able to find if it is 2 nd

gravidaResembles human face due to eyes face forward

Ears in final position, in line with the eyes



Weeks 1 7 - 20



Fetal movements like ³Fluttering´ or ³Butterflies´

Evident changes in skin and hair VernixCaseosa ± protect from constant exposure toAmniotic fluidLanugo ± help the vernix to adhere to the skinEye brows and head hair appearsBrown Fat ± back of neck, behind sternum & aroundkidneys



20 WEEKS

Weeks 2 1 24



Weeks 2 1 - 24Growth continues & gaining weight but thin & littlesubcutaneous fatTranslucent skin & looks red Because capillaries areclose to its fragile surface

Lungs produce surfactantCapillary network of alveoli increased but it isimmature. although some gas exchange is possible22 to 2 5 weeks fetus may survive with Intensive care



24 WEEKS

Weeks 2 5 28



Weeks 2 5 - 28

More likely to survive if born after 24 wks Because of maturation of lungs, pulmonary capillaries & CNS

Subcutaneous fat deposition make fetus plumper &smoother- skinned

Skin becomes less red

Re-opening of eyes, abundant head hair contd«



Blood formation shifts from spleen to bone marrowFetus assumes head-down position for 2 reasons* Uterus is like inverted egg.

* Fetal head is heavier than feet



Weeks 29-32

Smooth skin, pigmented according to raceLarger vessels are visible over abdomen but not smallcapillaries

Toenails present, finger nails extended to the finger TipsMore Subcutaneous rounding the body contoursIf born chances of survival is good



Weeks 33-38

Until birth growth continues but rate slows as full termapproaches.Gaining weight

Matured pulmonary system enables efficient &unlabored breath after birthWell-nourished term fetus is round with abundantsubcutaneous fatLanugo in forehead, upper back, upper arms

contd«



Vernix remain in groin and Axilla

Full term ranges from 36 to 40 weeks of fertilization or

38 to 42 weeks of gestational age

1.Conception

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