formation of germs/ gametes Flashcards
From zygote to germ layers
1.
Ectoderm (outside)
Differentiation into:
nervous system (brain, eyes, slain, -> mouth)
From zygote to germ layers
2.
Mesoderm (middle)
Differentiation into:
muscle (+heart), blood vessels, skeleton, urinary system
From zygote to germ layers
3.
Endoderm
Differentiation into:
digestive system (stomach, intestine, liver…)
Cleavage
zygote
Oogenesis
5th month of pregnancy:
Oogenesis (2n) + Mitotic devisions
->
Oocyte 1 (2n)
Birth: FREEZE!
-> Meiosis 1
Adolescence:
Oocyte 1 (1n) + polar body (1n)
OVALUATION
+ meiosis 2
- Oocyte 2 with ovum (1n)
- polar body (1n)
spermcells arrive
Spermatogenesis
5th month of pregnancy:
Spermatogonium (2n) + Mitotic devisions
Birth: -
spermatocyte 1 (2n)
Meiosis 1
2x spermatocyte 2 (1n)
meiosis 2
4x spermids (1n)
- > 4x spermcells (1n)
- > go to the ovum (oocyte 2)