Lecture 4 NROB60 Question And Answer

A comprehensive set of flashcards derived from the lecture on Early Nervous System Development, focusing on key terms, processes, and concepts.

What are the three germ layers in early embryonic development?

Ectoderm, mesoderm, and endoderm.

What role does the notochord play in early nervous system development?

Determines the position of the nervous system and is required for early neural differentiation.

What process leads to the formation of the neural tube?

Neurulation.

Which germ layer develops into the neural plate?

Ectoderm.

What is the significance of the neural crest?

It gives rise to sensory and autonomic ganglia of the peripheral nervous system.

What are the stages of neural tube formation?

Neural plate → neural groove → neural tube.

What structures do somites develop into?

Axial musculature and skeleton.

What are the primary divisions of the CNS that the neural tube differentiates into?

Forebrain, midbrain, hindbrain, and spinal cord.

How many primary brain vesicles are there?

Three.

Name the three primary brain vesicles.

Prosencephalon, mesencephalon, and rhombencephalon.

What does the term 'encephalon' mean?

Brain.

At what week does the neural tube fully close?

By 4 weeks of embryonic development.

What term refers to the process of development where the primary swellings differentiate into secondary brain vesicles?

Further development.

How many secondary brain swellings are there in total?

Five.

What regions does the telencephalon give rise to?

The cerebrum.

What regions does the diencephalon become?

The thalamus, hypothalamus, and retina.

What is the significance of the mesencephalon in brain development?

It does not divide further and becomes the midbrain.

Which structures result from the rhombencephalon?

Metencephalon (pons and cerebellum) and myelencephalon (medulla).

What is synaptogenesis?

The establishment of synaptic connections as axons and dendrites grow.

What is the average gestational period for myelination to begin?

Myelination begins around 24 weeks of gestation.

What is the main risk factor for neural tube defects?

Low levels of folic acid.

What is spinal bifida?

A condition where the caudal portion of the neural tube does not close completely.

What is the most severe type of spinal bifida?

Myelomeningocele.

What occurs in anencephaly?

Missing significant portions of the brain and skull, usually resulting from the failure of the rostral end of the neural tube to close.

What is the typical outcome for infants born with anencephaly?

Most do not survive long after birth, often leading to miscarriage or stillbirth.

What are the critical steps in neural tube defect prevention?

Ensure adequate folic acid levels prior to conception and during early pregnancy.

What is neurogenesis?

The mitotic division of nonneuronal cells to produce neurons.

What is the role of radial glial cells in brain development?

They guide migrating neurons to their final position in the brain.

What is the term for the process of programmed cell death during brain development?

Apoptosis.

What is the function of cell adhesion molecules (CAMs)?

They guide cell migration and axonal pathfinding.

What happens during synapse rearrangement?

The loss of some synapses and development of others to refine synaptic connections.

What is lissencephaly?

A brain malformation resulting in a smooth cortex without typical gyri and sulci.

Which gene is commonly linked to lissencephaly?

DCX gene.

What is histology?

The scientific study of the composition of tissues at a microscopic level.

What is the purpose of histological stains?

To provide contrast and reveal structures that cannot otherwise be seen.

What is a Nissl stain used for?

To outline all cell bodies in the tissue by staining RNA.

What does immunohistochemistry (IHC) enable researchers to do?

Target specific proteins in cells using antibodies.

What is a Golgi stain useful for?

Examining the precise shape and structure of individual neurons.

What is the purpose of cell types databases, like the one from the Allen Institute?

To categorize and study different types of brain cells based on shape, genes, and electrical properties.

What are the steps involved in histological processing of brain tissue?

Prepare, cut, mount sections, and run staining procedures.

What defines the structural organization and arrangement of cells within a tissue?

Cytoarchitecture.

What are the major phases of neuronal development according to the lecture?

Neurogenesis, cell migration, differentiation, synaptogenesis, neuronal cell death, synapse rearrangement.

What happens to neural connections as age increases during development?

The extent of neural connections and differentiation increases.

What are the two main types of cell staining used to visualize specific proteins?

Immunohistochemistry and immunofluorescence.

What is the impact of folic acid on neural tube closure?

Adequate levels of folic acid can significantly decrease neural tube defects.

What are the two types of cells derived from neural stem cells?

Neurons and glial cells.

Which type of cells primarily participate in myelination in the CNS?

Oligodendrocytes.

What are some common types of neural tube defects?

Spinal bifida and anencephaly.

When do the sulci and gyri of the cerebral cortex begin to emerge?

By the end of the second trimester.

What is the primary function of the thalamic nuclei?

They play a crucial role in relaying sensory and motor signals to the cerebral cortex.

How does the Nissl stain label cells?

It stains RNA-rich structures, revealing cell bodies but not fine details such as dendrites or axons.

What is the significance of the neural tube's closure timing?

Proper closure is critical to prevent neural tube defects.

What abnormal development do children with lissencephaly experience?

They typically have smooth brains and various cognitive and physical impairments.

What is the cause of most congenital neural tube defects?

A combination of genetic, nutritional, and environmental factors.

What advantage does the Golgi stain method have?

It allows for a clear view of the morphology of individual neurons.

What is the main benefit of using fluorescent dyes in modern neuronal studies?

It allows the examination of the precise shape and structure of individual neurons while relating structure to function.

What is neurogenesis primarily characterized by?

The mitotic division of nonneuronal cells to produce neurons.

How do progenitor cells contribute to the development of the CNS?

They give rise to neurons and glial cells in various brain regions.

What key process is essential for the proper formation of brain structure during development?

Cell migration.

What is a major characteristic of mature neurons regarding division?

Neurons themselves do not divide.

What can influence the differentiation of a neural cell?

The local environment and neighboring cells.

How long after conception does the majority of neurogenesis occur?

Most neurogenesis occurs during early embryonic development.

What is a critical time frame for ensuring adequate folic acid levels?

Before conception and during the first month of pregnancy.

What mechanisms guide cells during migration within the developing brain?

Radial glial cells provide a pathway for migrating neurons.

What happens to neurons that do not successfully establish adequate synaptic connections?

They undergo apoptosis or cell death.

How does the arrangement of neurons in the cerebral cortex affect its function?

Different layering of neurons allows for specialized processing of information.

What type of growth do filopodia contribute to in neuron development?

They are outgrowths from growth cones that help form synapses.

What is the relationship between synaptic activity and c-fos?

c-fos is expressed in neurons that are activated during synaptic activity.

What is the primary developmental change observed from newborn to 2 years old in the human cortex?

Increased complexity in neural connections and differentiation.

What structural feature defines the layers of the cerebral cortex?

Distinct lamination based on cellular density and organization.

How do neuronal migration patterns affect cortical structure?

Cells arrive in waves, creating distinct layers in the cortical structure.

What occurs to radial glial cells after neuronal migration is completed?

They either disappear or transform into astrocytes.

What condition is characterized by a failure of the rostral neural tube to close?

Anencephaly.

What type of tissue is targeted by immunohistochemistry?

Tissues containing specific proteins of interest.

What type of staining method helps visualize the overall organization of neurons?

Nissl stain.

How do neuroanatomists utilize atlases based on Nissl-stained sections?

To define distinct brain regions based on their cytoarchitecture.

What is the central role of the notochord in early CNS development?

It acts as a signaling center for the surrounding ectoderm.

In the context of brain development, what does apoptosis serve as?

An essential sculpting process during development.

What can be the consequences of improper cell migration during brain development?

Disorders such as lissencephaly can result from defective migration.

What is the function of cell adhesion molecules in neuron development?

They facilitate attachment during migration and axonal pathfinding.

Why is the timing of folic acid intake crucial during pregnancy?

To prevent neural tube defects before they occur.

How does synaptogenesis contribute to the establishment of neural networks?

By forming connections between neurons, enabling communication.

What role does myelination play in neuronal function?

It increases the speed of electrical signal transmission along axons.

What pathological effect may occur as a result of excess neurons in developing brains?

Congenital malformations due to impaired apoptosis.

What developmental phase encompasses both the formation and elimination of synapses?

Synapse rearrangement.

What does the presence of distinct cell layers in the cerebral cortex indicate?

Specialization in processing different types of information.

What hormonal influences may affect neuronal development?

Hormones can modulate growth and differentiation of neural cells.

What type of microscopy is generally used in immunofluorescence?

Fluorescent microscopy.

What is the role of the primary antibody in immunohistochemistry?

To bind specifically to the target protein within the tissue.

What is demonstrated by the use of the Allen Cell Types Database?

The diversity and classification of multiple brain cell types.

How can changes in myelination pattern affect brain functions?

Altered myelination can influence cognitive capabilities and speed of information processing.

What common outcome is observed in individuals with spinal bifida?

They may experience physical disabilities related to spinal cord injury.

What can be concluded about neural tube defects in terms of prevalence globally?

They occur more frequently on a global scale than in Canada.

Name a protective factor against spinal bifida during pregnancy.

Folic acid supplementation.

What happens to synapses that are not used during the developmental period?

They are eliminated through synaptic pruning.

What tissue type constitutes the majority of brain surface area?

Cerebral cortex.

What is a consequence of folic acid deficiency during the perinatal period?

Increased risk of neural tube defects and other developmental disorders.

What critical period in pregnancy is emphasized for the intake of nutrients?

The first trimester, especially the first month.

What does the failure of the neural tube to close lead to in terms of brain development?

It results in severe congenital malformations.

What key function does the cerebral cortex serve in the nervous system?

Higher cognitive functions such as thought, perception, and decision-making.