human embryonic development Flashcards
1
Q
weeks 1 to 3
A
- fertilization to gastrulation
- results in:
trilaminar embryo
2 signaling centers; AP axis
notochord
tissue specifications that are not obvious
2
Q
weeks 4 to 8
A
- organogenesis
- major external and internal structures are established
- results in:
shape of the embryo has human appearance
3
Q
organogenesis
A
- organs and tissues form germ layers
- cardio system functional
- exposure to teratogens cause congenital anomalies
- embryo folds into tube within a tube body plan
- pattern formation
4
Q
formation of mesoderm/endoderm organs
A
- occurs synchronously with neural tube formation
- anterior to posterior direction
- primitive streak regresses, leave notochord
5
Q
folding of the embryo
A
- 3 flat germ layers to cylinder (tube within a tube)
- lateral folds
- head fold
- tail fold
- folding results from rapid growth of embryo
6
Q
pattern formation
A
- 1) form body axes (break symmetry)
- 2) organization of embryo into smaller regions to create segments
- 3) segments develop specific characteristics
- 4) tissues and organs are produced