Gastrulation, Neurulation, and Early Human Nervous System Development

What initiates the first cell division in mammalian embryos?

Sperm-contained miRNA-34c binds to Bcl-2 to prevent cells from entering S phase.

What is the role of the primitive streak in mammalian gastrulation?

It serves as the initiation phase for gastrulation, establishing head mesendoderm and notochord.

What are the three germ layers established during gastrulation?

Endoderm, mesoderm, and ectoderm.

What processes are involved in gastrulation?

Initiation, internalization of the endoderm and mesoderm, and elongation of the anterior-posterior body axis.

What is the significance of Hox genes in embryonic development?

They are involved in anterior-posterior patterning and segmentation of the central nervous system.

What is the notochordal process?

A rod-like structure that forms along the midline of the embryo after cells migrate through the primitive streak.

What is Sonic Hedgehog (SHH) and its role in development?

A signaling molecule secreted by the notochord that influences neural tube patterning and cell differentiation.

What are the four developmental phases of the human brain?

Dorsal induction, ventral induction, neuronal proliferation and migration, and myelination.

What are the three fates of the ectoderm during gastrulation?

To become the neural plate, epidermis, and establish the neural crest.

What distinguishes primary neurulation from secondary neurulation?

In primary neurulation, the surface ectoderm and neural ectoderm are connected; in secondary neurulation, they develop independently.

What is the role of the notochord in BMP signaling?

The notochord modulates BMP activity for proper development of the neural tube and somites.

What are neuropores?

Sites where neural tube closure occurs, initiated at several distinct locations in humans.

What is the significance of the dorsal-ventral axis in embryonic development?

It is crucial for the proper patterning of the embryo and the formation of distinct structures.

What are neural tube defects?

Malformations resulting from the failure of the neural tube to close, affecting ~1 in 1,000 births.

What environmental factors can contribute to neural tube defects?

Maternal health issues, such as diabetes and obesity, as well as deficiencies in zinc and folic acid.

What is the role of Grainyhead transcription factors in neural tube closure?

They are major transcriptional regulators important for the closure of the neural tube.

What are the three primary vesicles formed in the anterior region of the CNS?

Prosencephalon, mesencephalon, and rhombencephalon.

What is the function of fibroblast growth factors (FGFs) in notochord development?

FGFs are involved in cell proliferation, differentiation, and migration during the formation of the notochord.

What is the notochordal plate?

A flattened structure formed from the fusion of the notochordal process with the endoderm.

What happens during the closure of the neural tube?

Neural tube cells stop expressing E-Cadherin and begin expressing N-Cadherin to facilitate fusion.

What is the role of nodal signaling in embryonic development?

Nodal proteins are involved in early mesoderm formation and help establish midline structures, including the notochord.

What are the hinge points in primary neurulation?

They are points where the neural plate bends and converges, critical for neural tube formation.

What is the significance of the anterior visceral endoderm in axis formation?

It plays a role in establishing the left-right axis during embryonic development.

What is the consequence of the regression of the primitive streak?

It contributes to the elongation of the anterior-posterior body axis.

What are the main cellular movements during gastrulation?

Internalization and migration of cells to form the endoderm and mesoderm.