Embryology: Development of Germ Layers

Flashcards covering key embryological terms, germ layer derivatives, closure timelines of neuropores, and associated developmental anomalies.

Neural crest cells (NCC)

Cells described as the 4th germ layer.

Primitive streak

Structure derived from the epiblast during gastrulation that gives rise to all 3 germ layers and normally disappears.

Somites

Structures formed by the thickening of paraxial mesoderm.

Cranial neuropore

Anterior opening of the neural tube that normally closes by Day 25.

Caudal neuropore

Posterior opening of the neural tube that normally closes by Day 28.

Sacrococcygeal teratoma

A developmental anomaly that occurs when the primitive streak persists.

Anencephaly

A developmental anomaly that occurs when the cranial neuropore fails to close.

Spina bifida

A developmental anomaly that occurs when the caudal neuropore fails to close.

Paraxial mesoderm

A subdivision of mesoderm that thickens to form somites.