PRENATAL DEVELOPMENT

The Female Reproductive System

UterusA muscular chamber

about the size and shape of a pear.

Located in a woman's abdomen, is a hollow, elastic reproductive organ, where a baby develops during pregnancy.

Female anatomyThe uterus - is a major

female hormone-responsive reproductive sex organ

Within the uterus fetus develops during gestation.

The term uterus =womb.

One end, the cervix, opens into the vagina; the other is connected on both sides to the Fallopian tubes.

Sperm Sperm is the male reproductive cell

Chief Characteristics:1. Tightly packed tip (acrosome) that contains 23

chromosomes that carry genetic information2. Short neck region3. Trail to propel it in its search for the ovum4. Microscopic

Fact: Remains capable of fertilizing egg for 24-48 hours

after ejaculation Of 200 million sperm that enter the vagina, only

about 200 survive the journey to the fallopian tubes, where fertilization occurs

Males, at birth, have in their testes those cells that will eventually produce sperm

Ovum (Egg) The ovum is the female reproductive cell

Chief Characteristics:1. Round2. .01 mm in diameter 3. Consistency of stiff jelly4. Contributes 23 chromosomes

Fact: Females already have 1-2 million primal eggs at birth Eggs usually fertilized about 12 hours after discharged

from the ovary or they die within 12-24 hours

• When a young woman reaches puberty, she begins to ovulate

• a process in which a mature egg cell (also called an ovum), ready for fertilization by a sperm cell, is released from one of the ovaries

ovulation

Her body prepares for a potential pregnancy every cycle, whether or not she want to actually conceive.

Under the influence of Follicle Stimulating Hormone (FSH), about 15 to 20 eggs start to mature in each ovary.

Although it averages about two weeks, the process to release an egg can take anywhere from about eight days to a month or longer to complete.

menstrual cycleOvulation occurs 14

days before the next menstruation.

As the average menstrual cycle lasts 28 days (starting with the first day of one period and ending with the first day of the next menstrual period), most women ovulate on day 14.

A menstrual cycle can vary between 21 to 38 days.

A woman is generally most fertile (able to become pregnant) a few days before, during, and after ovulation.

The corpus luteum remains behind on the interior ovarian wall, and starts releasing progesterone.

Progesterone quickly stops the release of all other eggs until the next cycle. The corpus luteum has a finite lifespan, of about 12 to 16 days.

If the egg does not become fertilized as it travels down the fallopian tube on its way to the uterus, the endometrium (lining of the uterus) is shed and passes through the vagina (the passageway through which fluid passes out of the body during menstrual periods; also called the birth canal), a process called menstruation.

Menstruation

Pregnancy

If the egg is fertilized by a sperm cell as it travels down the fallopian tube, then pregnancy occurs, it becomes attached to the lining of the uterus

In order for conception to occur, though, there must be three factors present: the egg, the sperm a medium in which the sperm can travel to reach

the fallopian tubes. Women produce cervical fluid under the

influence of increasing levels of estrogen in the first part of the cycle.

Sperms can live up to five days in fertile quality cervical fluid

3 Stages in prenatal development:

Germinal stageEmbryonic stageFetal stagePrinciples

Cephalocaudal principleProximodistal principle

First Stage: GerminalStarts at conception (fertilization) until

implantation 14 days.Conception process When the sperms

meets the egg (ovum) in the fallopian tube travel down into the uterus where it implants in the uterine lining and begin to grow (implantation).

ConceptionConception occurs

when the sperm meets and penetrates the ovum, or egg

spermsperm

ovumovum

Normally, only one sperms will succeed penetrating through the ovum wall.

When one sperms succeeded penetrating the ovum wall, a protective lining will form around it preventing other sperms to enter/penetrate.

The combination of ovum & sperms form zygote (with one nucleus).

Zygote will later develop into blastosist a complex organism with millions of cells with various functions.

Germinal stage (fertilization to 2 weeks)

Rapid cell division, increasing complexity and differentiation, and implantation

MitosisBlastocyst

Embryonic diskEctoderm, endoderm, mesoderm

TrophoblastPlacenta & umbilical cordAmniotic sac & chorion

Fertilization: the sperm and egg join in the fallopian tube to form a unique human being.

• a fertilized egg, only thirty hours after conception.

Zygotic Period(Conception - 1st Week)

A zygote is a fertilized egg with 46 chromosomes

Genetic potential determined at this time

Egg is 2.5 mm in diameter at end of 1st week

Mitosis, a process of cell division, occurs during this period

Early development of a human embryo

Early development of a human embryo

Embrio : blastosis burrows into the uterine lining

As soon as the fertilized egg burrows into the lining, it starts releasing a pregnancy hormone, HCG (Human Chorionic Gonadotropin) which sends a message back to the corpus luteum left behind on the ovarian wall.

HCG signals the corpus luteum to remain alive beyond its usual maximum of 16 days and continuing to release progesterone long enough to sustain the nourishing lining.

After several months, the placenta takes over, not only maintaining the endometrium, but providing all the oxygen and nutrients the fetus needs to thrive.

Cells Division

There are two type of cell division

Mitosis and meiosis Reproductive cells divide through meiosis

process, while all other body cells divide through the mitosis process

Cells Division Mitosis is cell division that results in the duplication of cells; the

daughter cells genetic copies of the parent cell. This cell multiplication allows for replacement of old cells, tissue repair, growth and development.

MitosisThe creation of new cells through duplication of chromosomes &

divisions of cells cells duplicates (From 1 24 16 32, etc)Cells developed into organs, brain, heart etc.

Growth & Development You grew from a zygote, or fertilized egg (the fusion of two cells: an

egg and a sperm) into an organism with trillions of specialized cells. Mitosis is the process that enabled you to grow and develop after

that fateful meeting of ovum and sperm became ‘you’. Cell Replacement

Cells must divide in order for an organism to grow and develop, but cell division is also required for maintenance, cell turnover and replacement.

Meiosis is Sex Cell (Gamete) Formation

In sexually reproducing organisms, some cells are able to divide by another method called meiosis.

Meiosis is a complex process by which gametes form; involves duplication and division of reproductive cells and their chromosomes.The number of chromosomes in cells divide into two’s, and each set of

cell will receive 1 from each sets of chromosomes makes up 23 sets.

This type of cell division results in the production of gametes (eggs or sperm).

Meiosis is much more complex than mitosis involves the duplication and subsequent division of chromosomes, meiosis involves two divisions of genetic material. As is the case in mitosis, in meiosis the cell duplicates its chromosome number prior to beginning cellular division. Then nuclear division, the sorting out of the genetic material, begins, and unfolds over the course of 2 cellular divisions that result in 4 gametes.

Meiosis is Sex Cell (Gamete) Formation

Gametes & GonadsGametes are haploid (1n) with half the number of chromosomes

than the progenitor cell that they arose from. These haploid sex cells arise in specialized reproductive tissue called the gonads. Ovaries (female gonads) and testes (male gonads) are the sites of meiosis.

Fertilization & DevelopmentSexual reproduction results in the merging of sperm and egg at

fertilization, and brings the chromosome count back to the 2n diploid number necessary for a zygote to have complete genetic information; 2 sets of genetic instructions in 23 pairs of chromosomes.

As cells divide, the zygote develops and grows into an embryo, fetus and beyond. These 23 pairs of chromosomes are duplicated with every cell division, and are the genetic material inside nearly every cell of the body.

What's the Difference between Mitosis & Meiosis

Mitosis is how the cells of our body make more cells for growth, development and repair.

Meiosis is how our body makes sex cells, or gametes (eggs or sperm).

Mechanisms of HeredityThe Genetic Code

Basis of heredity is a chemical called deoxyribonucleic acid (DNA), which contains all the inherited material passed from biological parents to children

Every cell except the sex cells has 23 pairs of chromosomes--46 in all

Genetic action that triggers growth of body and brain is often regulated by hormones

Mechanisms of heredityThe genetic code

DNA and chromosomesHuman genome23 pairs of chromosomes in every cell

(46 total) – except sex cellsMeiosis – division in sex cells (23 single

chromosomes)Mitosis – division in body cells

Genetic CodeGenetic information are kept in

chromosomes ie. A long & complex set of DNA molecules.

Genes is a segment of DNA molecules contains instructions for making protein.

Human being is said to have 100 trillions of cells in the body with specific functions; and is distributed through 46 chromosomes, ie. 23 from father & 23 from mother.

Genetic Foundation

Genotype (genetic makeup)

Phenotype (observable characteristics)

Hereditary composition of the zygote

What determines sex?

Autosomes – chromosome pairs 1- 22Sex chromosomes – 23rd pair of

chromosomesXX = femaleXy = males

Determination of a child’s sex

What Determines Sex?Sex chromosomes are either X chromosomes

or Y chromosomes When an ovum (X) is fertilized by an X-

carrying sperm, the zygote formed is XX, a female

When an ovum (X) is fertilized by a Y-carrying sperm, the resulting zygote is XY, a male

Choromosomes

Boy or girl?Chromosomes determine sex :

23 pairs of sex chromosomesFemale : XX pairs of sex chromosomesMale : XY pairs of sex chromosomes

FATHER=XY MOTHER=XX

XY (male) XX (female)

Patterns of Genetic Transmission

When an offspring receives two contradictory traits, only one of them, the dominant one shows itself

The expression of a recessive trait, occurs only when a person receives the recessive traits from both parents

Dominant and recessive inheritance

What Causes Multiple Births?Dizygotic (two-egg) twins=fraternal twinsMonozygotic (one-egg) twins=identical

twinsThe rise in multiple births is due in part to

a trend toward delayed childbearing

InfertilityInability to conceive a baby after 12 to 18

months of trying

Genetic and Chromosomal Abnormalities

Some defects are due to abnormalities in genes or chromosomes, which may result from mutations

Many disorders arise when an inherited predisposition interacts with an environmental factor, either before or after birth

Sex linked inheritance of a birth defect

Genetic Counseling and Testing

A chart can show chromosomal abnormalities and can indicate whether a person who appears normal might transmit

genetic defects to a child

Multiple births

Dizygotic and monozygotic twinsIncreased incidence of multiple births in

USWhy?

Delayed childrearingFertility drugs

Infertility: Alternative ways to parenthoodInability to conceive after 12 to 18 months of

tryingMultiple causes

Too few spermToo few ovaAbnormal ovaDisease of the uterine liningDeterioration in quality of ovaBlockage of the fallopian tubes

Assisted reproductionArtificial insemination

Artificial insemination by a donorIn vitro fertilization

Ovum transferSurrogate motherhood

What are concerns raised by surrogate motherhood?

Some Characteristics Influenced by Heredity

and Environment Adopted children's IQs are consistently closer to the IQs of

their biological mothers than to those of their adoptive parents and siblings.

Monozygotic twins generally look alike; they are also more concordant than dizygotic twins in their risk for such medical disorders as hypertension (high blood pressure), heart disease, stroke, rheumatoid arthritis, peptic ulcers, and epilepsy

Heredity seems to exert a strong influence on general intelligence and also on specific abilities

A strong hereditary influence on schizophrenia and autism, among other disorders; found in families

Nature and Nurture

2nd Stage in prenatal development stage

Embryonic Stage

Embryonic stage (2 to 8 weeks)

Rapid growth and development of major body systems and organs

A critical periodTrimestersSpontaneous abortion (miscarriage)Stillborn

Phases in pregnancy:

First trimester (week 1-12) 2nd Trimester (week 13 -24) 3rd Trimester (week 25 & above)

Proses PersenyawaanBapa (sperma) Ibu (Ovum)Bapa (sperma) Ibu (Ovum)½ sel (23 kromosom X or Y) ½ sel (23 kromosom X)½ sel (23 kromosom X or Y) ½ sel (23 kromosom X)

PersenyawaanPersenyawaan

zigotzigot

EmbrioEmbrio

FetusFetus

BabyBaby

2nd Stage: Embryonic Period(2nd Week - 2nd Month)

The phase after implantation. after the development of zygote and developing its blastosist.

Embryo composed of millions of cells with various functions (week 3-8)

2nd Stage: Embryonic Period(2nd Week - 2nd Month)

The differentiation of embryonic cells into layers marks the beginning of the embryo, or embryonic period

Period when all body systems form

Highly sensitive for susceptibility of congenital malformations, or abnormal conditions with which an infant is born

Embryonic Period: End of the 1st Month1/4 inch (6 mm)

long1 oz. WeightCrescent-shaped

with small limb buds on sides

Tail with tiny ridges

Rudimentary circulatory system is forming

Heart begins to beat

Growth acceleration

Embryonic Period:End of 2nd Month1.5 inches longBeginning of face,

neck, fingers, toes develop

Limb buds lengthenMuscles enlargeSex organs begin to

formRapid brain

developmentEmbryo is firmly

planted on uterine wall and is receiving nourishment from placenta and umbilical cord

Facial features are visible, including a mouth and tongue. The eyes have a retina and lens. The major muscle system is developed, and the unborn child practices moving. The child has its own blood type, distinct from the mother's. These blood cells are produced by the liver now instead of the yolk sac.

7 weeks

3rd stage: Fetal Stage(8 weeks to birth)

Embryo develops fetus (baby in the uterus).

Cells that represents eyes, head, body, hands, legs further develops larger.

The period of consumption until baby is born

40 weeks (sometimes 38-36 weeks).

Fetal stageIncreased detail of body parts and greatly

enlarged body sizeFinishing touchesFetal behavior

Ultrasound

Early Fetal Period: 3rd - 6th Month

Period of the fetus begins around the 3rd month and continues until delivery

Movement first becomes apparent to mother at this time

No new anatomical features appear during this period, yet still critical time

Early Fetal Period: 3rd Month

Rapid growth, 3 inches long at end of 3rd month

Sexual differentiation continues

Teeth buds emergeStomach and kidneys begin to

functionVocal cords appearReflex actions felt:

opens/closes mouth, clenches fist, sucks thumb

Early Fetal Period:4th Month

Most rapid growth rate (doubles in length to 6-8 inches)

6 oz. WeightHands fully shapedBony tissue begins to

form

Early Fetal Period:5th Month

Reaches 1/2 of birth length (8-10 inches)

Only 10% of birth weight (1/2 lb.)

Skin, hair, nails appearInternal organs grow and

assume proper anatomical positions

Pigmented hair on head & eyebrows appears

Early Fetal Period: 6th Month

13 inches long1 lb. WeightEyelids reopen and are

completedStructurally complete but

functionally immature

Later Fetal Period: 7th-9th Month/Birth

From the 7th month to birth, the fetus triples in weight

This is a period of filling out

Preparation for birth

Later Fetal Period:7th Month

A layer of adipose tissue begins to form under skin (serves as both insulator & food supplier)

Rapid 2-4 lb. Weight gain

14-16 inches long

Fetus is quiet for long periods of time

Brain more active and is increasing control over body systems

Later Fetal Period:8th Month

Fetus is more active (frequent changes in position)

Fatty deposits distributed

16-18 inches long

4-6 lbs.

Later Fetal Period:9th Month (Birth)19-21 inches long

6-8 lbs.

Birth process is initiated by placenta and contraction of uterine muscles

Birth generally occurs after week 40 of gestation (normal is 38-42 wks.)

Important parts in the uterus

Amniotic SacPlacentaAmniotic fluidUmbilical cord

Environmental Influences (Teratogens)

Maternal factorsTeratogenic – capable of causing birth defects

Maternal factors (continued)

Prescription and Nonprescription Drugs Medical drugs

ThalidomideDESAspirin

CaffeineCocaine, heroin, or methadone

Maternal factors (continued)

Tobacco/Nicotine Alcohol

Fetal alcohol syndromeFetal alcohol effects Sexually transmitted

diseases and other maternal illnessesAcquired immune deficiency syndrome

RadiationEnvironmental PolutionMaternal Diseases

Other Maternal factors

Exercise & Physical activityNutritionEmotional StressRh IncompartibilityMaternal age

Paternal factorsEnvironmentally caused defectsCocaine useAgeSmoking

Monitoring prenatal development

Ultrasound SonogramSonoembriology

AmniocentesisChorionic villus samplingEmbryoscopyPreimplantation genetic diagnosisUmbilical cord sampling (fetal blood

sampling)Maternal blood test

Prenatal careWhy is prenatal care important?How can it be improved?What is the relationship between prenatal care

and low birthweight and premature births?How can we tell whether a new baby is healthy

and is developing normally?What complications of childbirth can endanger

newborn babies, and what can be done to increase the chances of a positive outcome?

The birth processStages of childbirth

First stageSecond stageThird stageFourth stage

Electronic fetal monitoring

Stages of childbirth