what is preformationist?
theory of development in which prenatal life starts with a fully formed individual that gets bigger
- nativist
- false
canalization
length of pregnancies
gametes
haploid
fertilization and conception
zygote
fertilized egg with 23 chromosomes from mom and 23 from dad
what develops first in prenatal development?
four major developmental processes transform a zygote into an embryo and then into fetus
germinal period
embryonic period
fetal period
9th week - birth
- continued development of physical structures and rapid growth of the body
- increasing levels of behavior, sensory experience, and learning
monozygotic
dizygotic
is identical/ MZ twinning hereditary?
no, but tendency for hyper-ovulation can be passed down
is fraternal/ DZ twinning hereditary?
yes
amniotic sac/ placenta
the embryo layers in weeks 2-3
4 weeks
5.5-8 weeks
6-8 weeks
9 weeks
11 weeks
sexual differentiation