14. Weeks 3 to 8 - Embryonic Period

Question 1

What is grastrulation?

Answer 1

It is a process that establishes the 3 primary germ layers: ectoderm, mesoderm, and endoderm. This process is first indicated by the formation of the primative streak within the epiblast.

Question 2

What does the ectoderm evolve to?

Answer 2

Gives rise to neuroectoder and neural crest cells.

Question 3

What does the mesoderm evolve to?

Answer 3

Gives rise to paraxial mesoderm (35 pairs of somites), intermediate mesoderm, and lateral mesoderm.

Question 4

What is a chordoma?

Answer 4

It is a tumor that arises from remnants of the notochord found either intracranially or in the sacral region.

Question 5

What is a sacrococcygeal teratoma?

Answer 5

It is a tumor that arises from remnants of the primitive streak. It often contains various types of tissues (bone, nerve, hair, etc.)

Question 6

What is sirenomelia?

Answer 6

AKA Caudal Dysplasia, it refers to a constellation of syndromes ranging from minor lesions of the lower vertebrae to complete fusion of lower limbs as a result of abnormal gastrulation in which migration of mesoderm is disturbed. It is associated with VATER or VACTERL.