Prenatal Development

Pre-Natal PeriodStages of Pre-natal Development

Human Life begins at

Conception

Conception

• The union of a male sperm cell and a female egg cell to form a new organism.

Stages of Pre-Natal DevelopmentDivided into three periods:

– germinal period

– embryonic period

– fetal period

Germinal Period

Germinal Period

• Happens 2 weeks after conception

Includes:

• creation of the zygote;

• continued cell division; and

• the attachment of the zygote to the uterine wall

Germinal Period

• Rapid cell division

• By the end of the stage, the fertilized egg becomes a blastocyst and plants itself in the wall of the uterus.

Germinal period

Germinal Period

24 to 30 hours after fertilization

Germinal Period

36 hours after fertilization

Germinal Period


(2 days)

Germinal Period


(3 days)

Germinal Period


(4 days)

Germinal Period

4 to 5 days

Germinal Period

6 to 7 days

Germinal Period

11 to 15 days

Embryonic Period

Embryonic Period

• Happens 2 to 8 weeks after conception• Zygote becomes Embryo

Embryonic Period

• cell differentiation intensifies

• life-support systems for the embryo develop

• organs appear

Embryonic Period

• At the end of four weeks:–Embryo is 1/4 inch in length–Heart, digestive system, backbone and spinal

cord begin to form–Placenta (sometimes called "afterbirth") begins

developing

–The single fertilized egg is now 10,000 times larger than size at conception

Embryonic Period

6 Weeks 7 Weeks 8 Weeks

Embryonic Period

• At the end of 8 weeks:– Embryo is 1 1/8 inches in length

– Eyes, nose, lips, tongue, ears and teeth are forming

–Embryo is moving, although the mother can not yet feel movement

–Heart is functioning

Embryonic Period• Organogenesis

–the process of organ formation during the first two months of pre-natal development

Embryonic Period

• As these three layers form (endoderm, ectoderm, mesoderm), the support system for the embryo develop rapidly which are the:– placenta– umbilical cord– amnion

Embryonic Period

Embryonic Period

EmbryonicPeriod

Fetal Period

Fetal Period

• 2 to 7 months after conception

• Growth and development continue dramatically during this period.

3 months afterconception

Fetal Period

Fetal Period

• fetus is about 3 inches long• it has become more active by

moving its arms and legs, opens and closes its mouth, and move its head

• the genitals can now be identified as male or female

Fetal Period

• the following are distinguished:– face– forehead– eyelids– nose– chin– upper and lower arms– hands– lower limbs

Fetal Period

• fetus is about 6 inches long

• stronger pre-natal reflexes

• first arm and feet movement are felt by the mother

Fetal Development

• fetus is about 12 inches long

• structures of the skin have formed

• fetus is more active

Fetal Period

• Fetus is about 14 inches long

• eyes and eyelids are completely formed

• fine layer of hair covers the head

• grasping reflex present and irregular movements occur

Fetal Development• Fetus is 16 inches long• Taste buds have developed• Fat layers are forming• Organs are maturing• Skin is still wrinkled and red• If born at this time, he/she will be

considered a premature baby and require special care

Fetal Development

• Fetus is 19 to 20 inches long• The lungs are mature• Baby is now fully developed and can

survive outside the mother's body• Skin is pink and smooth• He/she settles down lower in the

abdomen in preparation for birth and may seem less active

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Christian F. Sebastian

Education

Prenatal Development