Week 4 - The Embryological Development of the CNS Flashcards

1
Q

What is Embryology?

A

Study of initial development of an embryo

In humans, all organ systems are developed by 8 weeks.

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2
Q

What is the embryonic period known for?

A

Period encompassing all organogenesis, highly susceptible to disruption and disorder

Development of the CNS is especially complex.

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3
Q

Define Neurulation.

A

The process where the neural plate forms the neural tube

Initiated by the notochord.

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4
Q

What is the significance of the notochord in CNS development?

A

Organizes surrounding tissues and provides structural support

Regulates left/right asymmetry and arterial/venous identity.

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5
Q

What are the primary vesicles formed by week 4?

A
  • Prosencephalon
  • Mesencephalon
  • Rhombencephalon
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6
Q

What occurs during Gastrulation?

A

Generation of the 3 germ layers: Ectoderm, Mesoderm, Endoderm

Occurs along the Primitive Streak.

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7
Q

What is neurogenesis?

A

Process by which neurons and glia proliferate, migrate, and are specified to form the mature brain

Includes synapse formation and myelination.

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8
Q

What are the three types of cell division by neural stem cells?

A
  • Asymmetric (PAX6)
  • Symmetric (EMX2)
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9
Q

Fill in the blank: The _______ is a transient structure that organizes surrounding tissues during neurulation.

A

notochord

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10
Q

True or False: The cranial neuropore closes at day 28 of development.

A

False

The cranial neuropore closes at day 24.

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11
Q

What are the derivatives of neural crest cells?

A
  • Neurons and glia of the PNS
  • Adrenal medulla
  • Melanocytes
  • Facial cartilage and bone
  • Corneal epithelium
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12
Q

What is the role of morphogens in CNS development?

A

Control the specification and development of multiple organ systems

Includes factors like SHH, Chordin, and Noggin.

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13
Q

What are Neural Tube Defects?

A

Developmental defects resulting from failure to close the neural tube

Includes conditions like Anencephaly and Spina Bifida.

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14
Q

What is Anencephaly?

A

Failure of the cranial neuropore to close, leading to absence of major brain aspects

Not viable; ethical debate surrounding organ donation.

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15
Q

What is Spina Bifida?

A

Most common neural tube defect caused by failure of closure of the caudal neuropore

Linked with hydrocephalus.

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16
Q

What is Craniorachischisis?

A

Most severe neural tube defect with both brain and spinal cord exposed

Multi-factorial causes include genetic and environmental disruptions.

17
Q

What is Microcephaly?

A

Smaller than normal head circumference due to lack of brain development

Associated with teratogens, including Zika virus.

18
Q

When do primary sulci initiate formation?

A

From week 12 to 28

Most gyri and sulci form in the second and third trimester.

19
Q

Fill in the blank: The _______ is the process of shaping and folding during neurulation.

A

Neuralation

20
Q

What is the significance of folic acid in neural tube development?

A

Linked to neural tube defects; mandated enrichment has reduced incidence

Possible role in epigenetic reprogramming.

21
Q

What is the term for smaller than normal head circumference due to lack of brain development?

A

Aly

Associated with many exposures to teratogens, especially viruses like Zika, and several genetic links including all viable trisomies.

22
Q

What is the primary defect associated with Holoprocencephaly (HPE)?

A

Failure of the procencephalon to segment at the midline

Occurs during weeks 5-6 of development and can be detected via ultrasound.

23
Q

What is the prognosis for Holoprocencephaly?

A

Generally poor, but less severe variants can be viable

Often suffer from seizures, endocrine disorders, and autonomic dysfunction.

24
Q

List the variants of Holoprocencephaly.

A
  • Lobar
  • Semi-lobar
  • Alobar

The degree of severity is reflected in the facial patterning of the fetus.

25
What severe facial defect can result from the most severe cases of Holoprocencephaly?
Cyclopia ## Footnote Less severe cases can co-occur with cleft lip and/or palate.
26
When does the development of the CNS and brain specifically start during embryonic development?
Midway through the 3rd week ## Footnote Neural tube formation is essential for brain development and fetal viability.
27
What is neurogenesis?
A divergent process resulting in a variety of neural cells required for brain maturation ## Footnote Essential for the proper development of the CNS.
28
What happens during the development of the CNS?
Vesicles develop and segmentation occurs, resulting in the adolescent brain ## Footnote Disruption can result in several severe defects.
29
What is neurulation?
The process of forming the neural tube ## Footnote The notochord plays a crucial role in this process.
30
Define specification in the context of neurogenesis.
The process by which neural cells become determined in their function ## Footnote Critical for the development of specific neural structures.
31
What are the primary and secondary vesicles in brain development?
* Primary vesicles: Prosencephalon, Mesencephalon, Rhombencephalon * Secondary vesicles: Telencephalon, Diencephalon, Metencephalon, Myelencephalon ## Footnote They develop into specific structures in the adult brain.
32
List pathologies associated with neurulation or neural tube defects.
* Spina bifida * Anencephaly * Encephalocele ## Footnote These defects can lead to significant neurological impairment.