1. Unit 8: Mammalian Reproduction

2. The male reproductive system
The male reproductive system produces sperm and transfers it to the female reproductive system.

3. The testes produce sperm and the male hormone, testosterone.
A hormone is a chemical that regulates body functions.

4. The female reproductive system
The female reproductive system produces eggs, ensures development of fertilized eggs, and gives birth.

5. In humans, the ovaries are about the size of a large olive.
Each ovary produce eggs, also called oocytes.
The release of oocytes is called ovulation

6. Development of the Human Embryo

7. Developmental History of a Human

8. Stages of Development
1. Fertilization 2. 3. 4. 5. 6.

9. 1. Fertilization

10. 2. Cleavage

11. 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

12. Stages of Development 1. Fertilization  Zygote 2. Cleavage 3. Morula4. 5. 6.

13. 3. Morula
Morula

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

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

16. A ZYGOTE contains all of the genetic information of the organism.
True
False

17. Approximately how many cells does a MORULA have?
Rank
Responses 1 2 3 4 5 6

18. Cleavage… begins approx. 12 hours post-fertilization.
involves mitosis only
Involves meiosis only
A and B
A and C

19. 4. Blastocyst

20. 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

21. 4. Blastocyst

22. What MUST to happen before the zygote can develop/grow?
Cleavage
Morula Stage
Fertilization
Placental Development
The gametes (egg and sperm) must fuse and go through meiosis before the zygote can develop.

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

24. Day 6
Three events happen

25. 1. Implantation

26. What part of the BLASTOCYST implants itself into the uterine wall?
Trophoblasts
Inner Cell Mass
The inner cell mass does not actually implant itself. It needs the trophoblasts to do the implanting.

27. The TROPHOBLASTS will form all of the following EXCEPT:
The umbilical cord
The fetus
The placenta
The amniotic fluid
The trophoblasts fill form everything EXCEPT for what will become the baby organism.

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

29. Stages of Development 1. Fertilization  Zygote 2. Cleavage 3. Morula
4. Blastocyst
5. Implantation (Day 6 into Week 2) 6.

30. 3. hCG is produced hCG is a hormone
hCG is human chorionic gonadotropin
It is produced by the trophoblasts starting on day 6
hCG causes endometrium (lining) of uterus to grow and proliferate
hCG prevents the menstrual cycle from occurring
This is why a female misses her periods when she is pregnant

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

32. If implantation occurs in the oviduct/ fallopian tube, the embryo
cannot develop properly
must be removed
could kill the mother
All of the above
This is called an ectopic pregnancy. There is not enough room for the embryo to develop and it must be removed or the oviduct can rupture, usually killing the mother.

33. Stages of Development 1. Fertilization  Zygote 2. Cleavage 3. Morula
4. Blastocyst
5. Implantation (Day 6 into Week 1)
6. Development (Embryo into Fetus)

34. Which 2 systems do you think the embryo needs to develop first?
Digestive & Endocrine
Endocrine & Cardiovascular
Cardiovascular & Nervous
Nervous & Immune
WHY?

35. Weeks 3-4
Development of cardiovascular and nervous systems

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

37. Embryo into 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.

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

39. By Week 8 an embryo has immature versions of all of its adult structures.
True
False
Weeks 8-38 of development are known as the “fetal period.” The embryo is now called a fetus.

40. A BLASTOCYST is only 16 cells big.
True
False

41. All of the following are true about a MORULA EXCEPT:
At this stage it enters the uterus.
It consists of approx. 16 cells.
Each cell contains a complete set of chromosomes.
It has a fluid-filled cavity.

42. The Fetal Period occurs…
Within the first 72 hrs.
On Day 6
By Week 2
During Weeks 8-38
During Weeks 38-42

43. Only 1 Cell Big, the ___________ contains all of the genetic information for the future organism.
Rank
Responses 1 2 3 4 5 6

44. In The Womb- Dogs
YouTube Video- NatGeo