3. How could a man become pregnant?

7. How could a man become pregnant?
Where would you put the embryo so that it is close to a source of nutrients?

8. placenta
A temporary organ (gland) forming from the outermost layer of the embryo and the lining of the mother’s uterus
What are the functions of the placenta?

10. 1. source of nourishment for embryo
Functions of the Placenta
1. source of nourishment for embryo
2. respiratory surface for embryo
3. excretory organ of embryo
4. attaches embryo/fetus to wall of uterus
5. secretes chorionic gonadotropin, progesterone, estrogen - regulation of pregnancy

11. Placenta
Fetus
Uterus
Umbilical Cord
Amniotic Fluid
Amniotic Sac (Amnion)

12. Umbilical Vein Umbilical Artery Placenta Chorionic Villus Fetal
Capillary

15. The blood of the embryo/fetus and the mother do not mix!
(embryonic and maternal circulatory systems are not connected )
How do substances get for the mom’s blood to the fetus and vice versa?

16. Substances diffusing through the placenta
From mom to embryo/fetus
Oxygen
Nutrients
Antibodies
From embryo/fetus to mom
Wastes
Human Chorionic Gonadotropin

17. Dangerous substances can pass through the placenta
Viruses (e.g. measles, AIDS)
Drugs (e.g. nicotine, prescription drugs)
Alcohol

18. What is the function of amniotic fluid?
6 weeks
- Keeps baby warm
- Lubrication keeps
body parts from
growing together
- Allows movement of baby (exercise)
- Shock absorber

31. Why do biologists classify egg-laying monotremes, such as the duckbill platypus, as mammals?
Monotremes have mammary glands, bodies covered with hair, and other
mammalian characteristics

32. Monotremes
Their eggs of contain a large amount of yolk.
Why do they have much more yolk than placental mammals?

33. Monotremes do not have a placenta.
Yolk provides nourishment for the developing embryo.
Placental mammals do not have much yolk in their eggs since the embryo gets nutrients through the placenta.

34. Mammals Monotremes lay eggs ex. echnida, platypus
Marsupials - ex. Kangaroo, oppossum
How does the embryo get nutrients?
Placentals - humans, whales
embryo completes development in
a pouch, attaches to nipple (milk)

36. Birth of kangaroo embryo, climb to pouch

38. Why have placental mammals been more successful than the nonplacental mammals?
developing young are protected within the uterus of the female until embryonic development is completed (internal development).

39. Who has a larger egg cell, an elephant or a chicken?

40. Why doesn’t an elephant need a large egg?
It has a placenta

41. Why does a chicken need a larger egg?
Chicken Egg - Trials of life – Arriving chapter 6
External development – no placenta

44. amniotic fluid
chorion
allantois
Chicken
embryo
airspace
shell
yolk sac
albumin
yolk

45.            Animal Internal Fertilization
External Fertilization
Internal Development
External Development
Amphibians
Reptiles
Birds
Mammals
nonplacentals
placentals           