1. Development of the Human Embryo
Dr. Nichols
Coronado High School

2. Developmental History of a Human

3. 1. Fertilization

4. 2. Cleavage

5. 2. Cleavage Begins ~ 12 hours post-fertilization
Zygote divides into 2 cells (mitosis)
46 chromosomes in zygote = 46 chromosomes in both daughter cells
2 cell into 4 cell stage (24 – 36 hours)
4 cell into 8 cell stage (36 – 72 hours)
16 cell stage -- Morula

6. 3. Morula
Morula

7. 3. Morula
~ 16 cell stage
Develops ~ 72 hours (3 days) from fertilization
Morula enters the uterus ~ after 3 days in oviduct

8. 3. Morula
72 hours post-
fertilization
entering uterus

9. Gestational Sac

10. 4. Blastocyst

11. 4. Blastocyst Morula, once entering the uterine cavity, floats freely
Morula begins to accumulate fluid and forms a cavity between its cells
Once cavity appears, it is now called a
blastocyst.

12. 4. Blastocyst

13. 4. Blastocyst Blastocyst has fluid-filled inner cavity
Evolves from morula on day 5

14. Implantation

15. Two Distinct Cell Types
Inner cell mass
trophoblasts

16. Two Distinct Cell Types
Trophoblasts – will form the invading placenta
Inner cell mass cells – will form the embryo

17. hCG is produced hCG is human chorionic gonadotropin
Large amounts are produced by the trophoblasts starting on day 6
hCG is a hormone
hCG causes endometrium of uterus to grow and proliferate
hCG prevents the menstrual cycle from occuring
This is why a female misses her periods when she is pregnant

18. Week 2 Implantation continues Erosion of maternal blood vessels
Complete emersion into
endometrium of uterus

19. Weeks 3-4
Development of CV and nervous systems

20. Weeks 3-4

21. Weeks 5-8
Embryo will develop all structures that an adult has by the end of week 8

22. Fetal Development

23. Fetal Development

24. Fetal Development

25. Fetal Development

26. Effects of Pregnancy Anatomical Changes

29. Embryo/Fetus Embryonic period is weeks 1-8
Fetal period begins on week 9 and goes until birth at 38 weeks.
Embryonic period is characterized by development of structures (organs).
Fetal period is characterized by growth of those structures.

30. Fetal Period
9-12
13-16
17-20
21-38

32. Placenta
The placenta is a structure that develops in your uterus during pregnancy. The placenta provides oxygen and nutrients to your growing baby and removes waste products from your baby's blood.
It attaches to the wall of your uterus, and your baby's umbilical cord arises from it. In most pregnancies, the placenta attaches at the top or side of the uterus.

33. Placenta

36. Cartoons of the Day!

37. Cartoons of the Day!

38. Cartoons of the Day!

39. Cartoons of the Day!

40. Cartoons of the Day!

41. Cartoons of the Day!

42. Background Hepatitis B Acute Disease 1% mortality rate
85-90% complete resolution
10-15% chronically infected
Hepatitis B Chronic Disease
Persistent e antigen
Active viral DNA synthesis
4,000 to 5,000 die annually secondary to chronic liver disease

43. Background Hepatitis B Horizontal transmission
Parenteral contact (IV drug use)
Sexual contact (25% regular contacts will convert)
Vertical transmission
Transmission to neonate
World-wide #1 transmission

44. Frequency in Pregnancy
In the United States
Acute Hepatitis B
1-2/1,000 pregnancies
Chronic carrier
5-15/1,000 pregnancies

45. Cartoons of the Day!

46. Cartoons of the Day!

47. Cartoons of the Day!

48. Cartoons of the Day!

49. Breaking News!!!!
The new church went through its last structure inspection yesterday. Daniel Anderson was the man responsible for commissioning the new property.
Mr. Anderson reached out to our Chief yesterday to report some weird findings.
He said: “While the structure was safe and passed code, there were some out of the ordinary aspects, not typically found in a church. All I know is there is three hollow columns into the tabernacle that are surrounded by heating coils. There has also been digging specialized crews on site for a while now.”

50. Church Tabernacle