The document summarizes the three main stages of pre-natal development: the germinal period, embryonic period, and fetal period. The germinal period occurs within the first two weeks after conception and involves cell division and implantation in the uterus. The embryonic period lasts from weeks 2 to 8, where the zygote becomes an embryo and organs begin to form. The fetal period is from months 2 to 7, where growth and development accelerate dramatically and the fetus becomes increasingly active and developed.

2. Pre-Natal Period
Stages of Pre-natal Development

3. Human Life begins at
Conception

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

5. Stages of Pre-Natal Development
Divided into three periods:
– germinal period
– embryonic period
– fetal period

6. Germinal Period

7. 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

8. 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.

9. Germinal period

10. Germinal Period
24 to 30 hours after
fertilization

11. Germinal Period
36 hours after
fertilization

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

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

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

15. Germinal Period
4 to 5 days

16. Germinal Period
6 to 7 days

17. Germinal Period
11 to 15 days

18. Embryonic Period

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

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

22. 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

23. Embryonic Period
6 Weeks 7 Weeks 8 Weeks

25. 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

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

28. 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

29. Embryonic Period

30. Embryonic Period

31. Embryonic
Period

32. Fetal Period

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

34. 3 months after
conception
Fetal Period

35. 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

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

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

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

42. 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

44. 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

46. 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

50. End
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Copyright © 2014
Christian F. Sebastian