Glossary of Key Terms in Neurulation and Development

Apical Constriction

An asymmetrical change in cell shape where the apical (top) side of a cell narrows, contributing to tissue bending and folding during development.

BMP (Bone Morphogenic Protein)

A family of chemical signals (morphogens) that play a crucial role in preventing hinge point formation and influencing cell fate in the ectoderm.

CNS (Central Nervous System)

Comprised of the brain and spinal cord, formed from the neural tube.

Cavitation

The process in secondary neurulation where a solid mass of cells forms a hollow tube (lumen) internally.

DLHP (Dorso-Lateral Hinge Point)

A hinge point formed in the neural folds during primary neurulation, facilitated by Noggin, crucial for the lateral bending and fusion of the neural folds.

Ectoderm

The outermost of the three primary germ layers in early embryonic development, from which the neural tube, neural crest, and surface ectoderm are derived.

Lumen

The hollow space formed inside the neural tube after its formation.

Mesenchymal

Referring to cells that are loosely organized and have the ability to migrate, characteristic of neural crest cells.

MHP (Medial Hinge Point)

A hinge point formed at the midline of the neural plate during primary neurulation, facilitated by SHH, crucial for the initial bending of the neural plate.

Morphogens

Chemical signals that diffuse through tissues and establish concentration gradients, guiding cell differentiation and tissue patterning. Examples include SHH and BMP.

Neural Crest

A transient embryonic cell population derived from the ectoderm at the edges of the neural plate. These mesenchymal cells migrate to form various tissues, including components of the PNS.

Neural Fold

The raised edges of the neural plate that fold inward and eventually fuse to form the neural tube during primary neurulation.

Neural Groove

A midline depression that forms in the neural plate before the neural folds elevate.

Neural Plate

A thickened region of the ectoderm that serves as the precursor to the neural tube during primary neurulation.

Neural Tube

The embryonic precursor of the brain and spinal cord (CNS), formed during neurulation.

Neurula

An embryo that is undergoing the process of neurulation.

Neurulation

The developmental process in which the neural plate forms, folds, and fuses to create the neural tube.

Noggin

A morphogen secreted by the neural folds that binds to and inhibits BMP, essential for DLHP formation and neural fold fusion.

Notochord

A rod-like structure beneath the neural plate that secretes SHH, crucial for inducing the MHP.

PNS (Peripheral Nervous System)

Comprised of nerves and ganglia outside the brain and spinal cord, largely formed from neural crest cells.

Primary Neurulation

One of the two modes of neurulation, characterized by the folding and fusion of the neural plate to form the neural tube.

Secondary Neurulation

One of the two modes of neurulation, characterized by the formation of a solid cord of cells that then cavitates to form a hollow neural tube.

SHH (Sonic Hedgehog)

A morphogen secreted by the notochord that plays a critical role in inducing the MHP during primary neurulation.

Sox Transcription Factors (Sox 1, 2, & 3)

A family of transcription factors expressed in the neural tube that activate genes for neural plate formation and inhibit BMP signaling, establishing neural precursor identity.

Surface Ectoderm

The part of the ectoderm that gives rise to the epidermis and other skin structures, characterized by high BMP levels.

Transcription Factor

A protein that binds to specific DNA sequences, thereby controlling the flow (or transcription) of genetic information from DNA to messenger RNA.