19 Embryology (Primary Germ Layers)

Question 1

When are the primary germ layers formed?

Answer 1

in week 2-3 of the embryonic phase, in a process called gastrulation

Question 2

What are the 3 primary germ layers, and what do they give rise to?

Answer 2

Ectoderm (nervous system, epidermis)

Endoderm (epithelia of respiratory, digestive and urogenital systems)

Mesoderm (muscle, connective tissues, most other tissues in the body)

Question 3

What are somites?

Answer 3

Cuboidal blocks of mesoderm that form in pairs on either side of the neural tube

Somites give rise to most of the axial skeleton as well as associated muscle and dermis

Question 4

What are the 3 components of somites?

Answer 4

Sclerotome: vertebra at associated level

Myotome: muscle at associated level

Dermatome: skin at associated level