human embryonic development

Question 1

weeks 1 to 3

Answer 1

• fertilization to gastrulation
• results in:
  trilaminar embryo
  2 signaling centers; AP axis
  notochord
  tissue specifications that are not obvious

Question 2

weeks 4 to 8

Answer 2

• organogenesis
• major external and internal structures are established
• results in:
  shape of the embryo has human appearance

Question 3

organogenesis

Answer 3

• 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

Question 4

formation of mesoderm/endoderm organs

Answer 4

• occurs synchronously with neural tube formation
• anterior to posterior direction
• primitive streak regresses, leave notochord

Question 5

folding of the embryo

Answer 5

• 3 flat germ layers to cylinder (tube within a tube)
• lateral folds
• head fold
• tail fold
• folding results from rapid growth of embryo

Question 6

pattern formation

Answer 6

• 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