Embryology And Fetal Screening

Question 1

What are the different steps for development of blastocyst?

Answer 1

Day 1 - fertility
Day 2 - cleavage
Day 3 - compaction
Day 4 - differentiation
Day 5 - cavitation
Day 6 - zoa hatching
Day 7 - implantation
Day 9 - cell mass differentiates
Day 12 - bilaminar disc formation
Day 14 - mesoderm formation
Day 18 - mesoderm spreads
Day 23 - amniotic sac enlarges

Question 2

What are the 3 germ layers and where are they found?

Answer 2

Ectoderm - nervous system, retina of the eye, special sense epidermis
Mesoderm - connective tissue, heart, spleen, muscles, skull
Endoderm - Lungs, trachea, liver, pancreas, bladder, alimentary canal