Neurulation

What is neurulation?

Formation of spinal cord precursors from the epiblast ectoderm.

When does neurulation begin?

During the latter portion of gastrulation, as the primitive streak regresses.

What structure marks the beginning of neurulation?

Formation of the neural plate.

What marks the end of neurulation?

Closure of the neural tube.

What does the neural tube eventually become?

The central nervous system (CNS).

True or False: Neurulation is specific to chordates.

True

1 multiple choice option

What type of cells form the notochord?

Mesoderm cells activated by Hensen's node.

What is the main role of the notochord during development?

It induces the overlying epiblast ectoderm to initiate central nervous system (CNS) formation

Is the notochord a permanent structure?

No — it becomes encased in vertebrae.

From which germ layer does the primordial CNS form?

Ectoderm

What is the process by which the neural tube forms?

Invagination of the neural plate, followed by closure into the neural tube.

What triggers the start of neurulation?

Induction of neural plate cells by the notochord.

What structural changes happen during neurulation?

The neural plate bends into a neural groove, which then pinches off to form the neural tube.

What four major steps occur during neurulation?

Epiblast cells differentiate into mesoderm inside the blastocoel.

Hensen's node activates mesoderm to form the notochord.

Notochord induces the ectoderm to form the neural plate.

Neural plate invaginates, forms the neural groove, then closes into the neural tube.

What happens inside the neural tube after closure?

Cells proliferate and differentiate into the CNS.

What difference is seen between anterior and posterior ends of the neural tube?

Anterior thickens into presumptive brain structures.

Posterior remains tube-like and forms the spinal cord.

What two body cavities are formed around the developing embryo during neurulation?

Dorsal cavity: Amniotic cavity

Ventral cavity: Yolk sac cavity

As the primitive streak regresses, what key structure completes formation?

The notochord.

How does neurulation progress along the body axis?

From anterior to posterior.

True or False: Brain and spinal cord structures form simultaneously during neurulation.

False — brain structures form earlier (anteriorly), spinal cord structures form later (posteriorly)

1 multiple choice option

How does the neural tube change during early brain development?

It constricts and thickens, leading to regional differentiation.

What major transformation happens to the neural tube?

It progresses from a simple structure to a complex brain divided into regions.

What are the three primary brain vesicles formed early during development?

Forebrain (Prosencephalon)

Midbrain (Mesencephalon)

Hindbrain (Rhombencephalon)

How does the brain evolve from the 3-part structure?

It divides into five brain regions.

Name the five secondary brain vesicles formed after division.

Telencephalon

Diencephalon

Mesencephalon (remains undivided)

Metencephalon

Myelencephalon

Which brain vesicle does not divide during brain development?

Mesencephalon