Human development begins at conception. There are three main periods of prenatal development: the germinal period lasts 2 weeks after conception and involves cell division and implantation; the embryonic period lasts from weeks 2-8 and organs begin to form; and the fetal period lasts from months 2-9 where growth and maturation continue dramatically. By the end of the fetal period, the fetus is fully developed and capable of surviving outside the womb.

1. DEVELOPMENTAL PSYCHOLOGY

2. Human Life begins at
Conception

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

4. PRENATAL DEVELOPMENT
The most dramatic and extensive transformation of one’s entire life, starts from
conception and continuous till death.
Prenatal development is often divided into three main periods,
The first two weeks are called the germinal period
The third through the eighth week is the embryonic period
From then until birth is the fetal period.

5. GERMINAL PERIOD
• Happens 2 weeks after conception, includes:
 creation of the first human cell, zygote; resulting from
union of male sperm with female ovum into her fallopian
tube
 continued cell division
 And the attachment of the zygote to the uterine wall
 Rapid cell division
 By the end of the stage, the fertilized egg becomes a
blastocyst and plants itself in the wall of the uterus.

6. Germinal period

7. Germinal Period
24 to 30 hours after
fertilization

8. Germinal Period
36 hours after
fertilization

9. Germinal Period
48 hours after
fertilization
(2 days)

10. Germinal Period
72 hours after
fertilization
(3 days)

11. Germinal Period
96 hours after
fertilization
(4 days)

12. Germinal Period
4 to 5 days

13. Germinal Period
6 to 7 days

14. Germinal Period
11 to 15 days

15. Embryonic Period
• Happens 2 to 8 weeks after conception
• Zygote becomes Embryo

16. Embryonic Period
 cell differentiation
intensifies
 life-support systems for the
embryo develop
 organs appear

18. 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

19. Embryonic Period
6 Weeks 7 Weeks 8 Weeks

21. Embryonic Period
• At the end of 8 weeks:
– Embryo is 1 1/8 inches in length
– Eyes, nose, lips, tongue, ears are forming
–Embryo is moving, although the
mother can not yet feel movement
–Heart is functioning

23. Embryonic Period
• Organogenesis
–the process of organ formation during the first two
months of pre-natal development

24. 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

25. Embryonic Period

26. Embryonic Period

27. Embryonic
Period

28. Fetal Period
• 2 to 7 months after
conception
• Growth and development
continue dramatically during
this period.

29. 3 months after
conception
Fetal Period

30. 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

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

33. Fetal Period
• fetus is about 6 inches long
• stronger pre-natal reflexes
• first arm and feet movement
are felt by the mother

35. Fetal Development
• fetus is about 12 inches
long
• structures of the skin have
formed
• fetus is more active

37. 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

39. 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

41. 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