240923 INTRO TO HUMAN DEVELOPMENT

Question 1

Name and describe the 4 big embryonic milestones and state how many days post fertilisation each one occurs

Answer 1

Cleavage - zygote divides to become a 32-64 cell blastocyst 4-5 days post fertilisation

Implantation - blastocyst becomes embedded in uterine endometrium, which closes around it, 8 days post fertilisation

Gastrulation - on day 15, an invagination gives rise to the primitive streak, which causes the embryo to change shape, thereby allowing cells to get into the correct position to give rise to the three germ layers (ectoderm, mesoderm and endoderm) that will form all the different tissues in the body.

Question 2

Name the 3 origins of birth defects

Answer 2

Genetic - inherited or de novo mutations

Environmental - exposure to teratogens

Infectious - maternal disease