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PRENATAL DEVELOPMENT
The Female Reproductive
System
 Uterus
 A 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 anatomy
 The uterus - is a major
female hormoneresponsive
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 is the male reproductive cell
Sperm
Chief Characteristics:
1. Tightly packed tip (acrosome) that contains 23
chromosomes that carry genetic information
2. Short neck region
3. Trail to propel it in its search for the ovum
4. 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. Round
2. .01 mm in diameter
3. Consistency of stiff jelly
4. 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
ovulation
• 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
 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 cycle
 Ovulation 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.
Menstruation
 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.
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 stage
 Embryonic stage
 Fetal stage
 Principles
 Cephalocaudal principle
 Proximodistal principle
First Stage: Germinal
 Starts 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).
Conception
 Conception occurs
when the sperm
meets and penetrates
the ovum, or egg
sperm
ovum
 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
 Mitosis
 Blastocyst
 Embryonic disk
 Ectoderm, endoderm, mesoderm
 Trophoblast
 Placenta & umbilical cord
 Amniotic 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.
 Mitosis
 The creation of new cells through duplication of chromosomes &
divisions of cells  cells duplicates (From 1 24  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 & Gonads
 Gametes 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 & Development
 Sexual 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 Heredity
 The 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 heredity
 The genetic code
 DNA and chromosomes
 Human genome
 23 pairs of chromosomes in every cell
(46 total) – except sex cells
 Meiosis – division in sex cells (23 single
chromosomes)
 Mitosis – division in body cells
Genetic Code
 Genetic 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- 22
 Sex chromosomes – 23rd pair of
chromosomes
 XX = female
 Xy = 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 Xcarrying sperm, the zygote formed is XX, a
female
 When an ovum (X) is fertilized by a Ycarrying sperm, the resulting zygote is XY, a
male
Choromosomes
 Boy or girl?
 Chromosomes determine sex :
 23 pairs of sex chromosomes
 Female : XX pairs of sex chromosomes
 Male
: XY pairs of sex chromosomes
FATHER=XY
XY (male)
MOTHER=XX
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 twins
 Monozygotic (one-egg) twins=identical
twins
 The rise in multiple births is due in part to
a trend toward delayed childbearing
 Infertility
 Inability 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 twins
 Increased incidence of multiple births in
US
 Why?
 Delayed childrearing
 Fertility drugs
Infertility: Alternative
ways to parenthood
 Inability to conceive after 12 to 18
months of trying
 Multiple causes
 Too few sperm
 Too few ova
 Abnormal ova
 Disease of the uterine lining
 Deterioration in quality of ova
 Blockage of the fallopian tubes
Assisted reproduction
 Artificial insemination
 Artificial insemination by a donor
 In vitro fertilization
 Ovum transfer
 Surrogate motherhood
 What are concerns raised by surrogate
motherhood?
Nature and Nurture
 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
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 period
 Trimesters
 Spontaneous abortion (miscarriage)
 Stillborn
Phases in pregnancy:
 First trimester (week 1-12)
 2nd Trimester (week 13 -24)
 3rd Trimester (week 25 & above)
Proses Persenyawaan
Bapa (sperma)
½ sel (23 kromosom X or Y)
Ibu (Ovum)
½ sel (23 kromosom X)
Persenyawaan
zigot
Embrio
Fetus
Baby
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 Month
 1/4 inch (6 mm)






long
1 oz. Weight
Crescent-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 Month
 1.5 inches long
 Beginning of face,





neck, fingers, toes
develop
Limb buds lengthen
Muscles enlarge
Sex organs begin to
form
Rapid brain
development
Embryo is firmly
planted on uterine wall
and is receiving
nourishment from
placenta and umbilical
cord
7 weeks
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.
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 stage
 Increased detail of body parts and greatly
enlarged body size
 Finishing touches
 Fetal 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 emerge
Stomach and kidneys begin to
function
Vocal cords appear
Reflex actions felt:
opens/closes mouth, clenches
fist, sucks thumb
Early Fetal Period:4th Month
 Most rapid growth rate
(doubles in length to 68 inches)
 6 oz. Weight
 Hands fully shaped
 Bony 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 appear
Internal organs grow and
assume proper
anatomical positions
Pigmented hair on head &
eyebrows appears
Early Fetal Period: 6th Month
 13 inches long
 1 lb. Weight
 Eyelids reopen and are
completed
 Structurally 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 Sac
 Placenta
 Amniotic fluid
 Umbilical cord
Environmental Influences
(Teratogens)
 Maternal factors
 Teratogenic – capable of causing birth defects
Maternal factors
(continued)
 Prescription and Nonprescription
Drugs
 Medical drugs
 Thalidomide
 DES
 Aspirin
 Caffeine
 Cocaine, heroin, or methadone
Maternal factors
(continued)
 Tobacco/Nicotine
 Alcohol
 Fetal alcohol syndrome
 Fetal alcohol effects Sexually transmitted
diseases and other maternal illnesses
 Acquired immune deficiency syndrome
 Radiation
 Environmental Polution
 Maternal Diseases
Other Maternal factors
 Exercise & Physical activity
 Nutrition
 Emotional Stress
 Rh Incompartibility
 Maternal age
Paternal factors
 Environmentally caused defects
 Cocaine use
 Age
 Smoking
Monitoring prenatal
development
 Ultrasound
 Sonogram
 Sonoembriology
 Amniocentesis
 Chorionic villus sampling
 Embryoscopy
 Preimplantation genetic diagnosis
 Umbilical cord sampling (fetal blood
sampling)
 Maternal blood test
Prenatal care
 Why 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 process
 Stages of childbirth
 First stage
 Second stage
 Third stage
 Fourth stage
 Electronic fetal monitoring
Stages of childbirth