Neuro II embryo

What is fertilization in the context of nervous system development?

The process of the sperm fertilizing an oocyte resulting in a zygote.

What is the morula?

An early cleavage stage of the zygote consisting of a solid ball of cells.

What is the blastocyst?

A stage in embryonic development consisting of a hollow ball of cells that implants into the uterine wall.

During which week does gastrulation occur?

Gastrulation occurs in the 3rd week of embryonic development.

What forms during gastrulation?

The three germ layers: endoderm, mesoderm, and ectoderm.

What is the role of the epiblast during gastrulation?

They migrate through the primitive streak to form mesenchyme (embryonic CT).

What is a sacrococcygeal teratoma?

A tumor that forms from the persistence of the primitive streak.

What percentage of births is affected by sacrococcygeal teratoma?

It occurs in 1 in 35,000 births.

What does the endoderm give rise to?

The epithelium of the respiratory and GI tract.

What develops from the mesoderm?

Cranium, muscles, urogenital system, heart, spleen, blood, bone.

What does the ectoderm form?

Skin, hair, and the nervous system.

What is the notochord?

A structure formed from mesodermal cells that signals the formation of the neural plate.

What key event triggers the formation of the neural plate?

Notochord formation.

What is neurulation?

The process of forming the neural plate from ectoderm.

What does the neural tube form during embryonic development?

It gives rise to the central nervous system (CNS).

When does the neural tube close?

It closes and begins to flex at day 22 of development. Cranial end closes before the caudal end.

What is craniorachischisis totalis?

A defect involving failure of the entire neural folds to differentiate and close.

What is spina bifida?

A defect that occurs when the neural arches fail to fuse.

What is the difference between spina bifida occulta and spina bifida cystica?

Spina bifida occulta has no vertebral arch and no underlying neurological involvement, while spina bifida cystica involves protrusion of the meninges or spinal cord.

How common is spina bifida cystica?

It occurs in 1 in 1000 births.

What are neurocristopathies?

Malformations due to defective development and migration of neural crest cells.

What is Treacher Collins Syndrome?

A genetic defect characterized by underdeveloped zygomatic bones, small mandible, and malformed ears.

What is DiGeorge Syndrome?

A genetic condition that causes craniofacial defects, immune deficiencies, and cardiac abnormalities.

What cells form the layers of the neural tube?

Neuroepithelial cells.

What do the ventricular layer of the neural tube give rise to?

Neuroblasts that migrate into the mantle layer.

What does the mantle layer contain?

Neuronal cell bodies, which make up the gray matter of the CNS.

What is the marginal layer of the neural tube?

It consists of the nerve fibers that make up the white matter of the CNS.

What do glioblasts turn into?

Astrocytes and oligodendrocytes.

What forms the choroid plexus?

Ependymal cells and vascular mesenchyme.

During spinal cord development, what does the alar plate form?

The dorsal horn associated with sensory functions.

What does the basal plate develop into?

The ventral horn associated with motor functions.

What is the intermediate cell column involved in?

The sympathetic and parasympathetic nervous systems.

What do the axonal sprouts from ventral horn cells form?

The ventral root of spinal nerves.

Where do the sensory neurons' cell bodies reside?

In the dorsal root ganglion (DRG) formed from neural crest cells.

What is the function of pseudounipolar cells?

They transmit sensory information to the CNS.

When do somites begin forming?

19-20 days from paraxial mesoderm.

What do somites contribute to?

The formation of the axial skeleton.

What are the three derivatives of somites?

Sclerotome (tendon, cartilage, bone), myotome (muscle), and dermatome (skin).

What do the cerebral hemispheres develop from?

The telencephalon.

What structures are derived from the diencephalon?

Thalamus, epithalamus, hypothalamus, infundibulum, and posterior pituitary.

What is the significance of the mesencephalon?

It develops into the midbrain.

What regulates the shape of the adult brain during development?

The cranial neural tube's flexures.

What condition results from the blockage of cerebrospinal fluid (CSF)?

Hydrocephalus.

When does myelination occur in development?

From the 4th month of development to the 1st year.

What happens to the length of the vertebral column as the spinal cord develops?

The vertebral column and dura mater lengthen faster than the spinal cord.

What is the brain size at birth in relation to adult size?

The brain is 25% of its adult size at birth.

What occurs in the cerebrum during the final part of fetal life?

Rapid growth, leading to the appearance of gyri and sulci.