Placentation Flashcards
reproduction occurs at the interface of
aquatic and terrestrial (air) environments
what does a fetus need? (5)
- protective environment
- shock absorbing
- oxygen, nutrition
- transfer of maternal immunity
- waste removal
amniotes include:
tetrapod vertebrates:
- amphibians
- reptiles
- mammals
what is the division of mammals
prototheria and theria (theria subdivided into metatheria and eutheria)
what type of mammals are placental mammals
eutheria (a type of theria)
what are the initial steps of organization of the embryo (very early on)
zygote (fertilized ovum) -> morula (16+ cells) -> blastula (consisting of the blastema and the blastocoel) -> blastocyst
the chorion = ____________ + ________________
trophoblasts + mesoderm
trophoblasts are in contact with
the mother
what does the endoderm become
the gut and yolk sac
the umbilical cord = _________, ___ arterie(s) and ___ vein(s)
urachus; 2 arteries; 1 vein
what are the definitions of when an embryo becomes a fetus
1) when it starts to move
2) when you can identify the species
the blood supply of the placenta is (volume/pressure)
high volume, low pressure
what types of animals have yolk-sac prominent placentas
1) carnivores
2) marsupials
3) rodents and lagamorphs
what is the role of the endometrial glands
secrete histotroph that the chorioallantois picks up
what are the 4 main placental structures
1) chorion and arrangement
2) allantoic cavity and membrane
3) amniotic cavity and membrane
4) umbilical cord and components
