NeuroAnatomy - Lecture 14 - Neural Tube Development

Question 1

What is the neural tube?

Answer 1

primitive embryonic tube-like structure that is the precursor to the CNS

Question 2

What is the process called that develops the neural tube?

Answer 2

Neurulation during first month of embryonic development

Question 3

How do neural tube defects occur?

Answer 3

when the neural tube fails to close during neurulation in either rostral or caudal neuropores

Question 4

What are the embyronic stages leading to neural tube development?

Answer 4

Fertilization/Implantation, Gastrulation, Neurulation

Question 5

What is the time period of fertilization?

Answer 5

0-7 days before implantation

Question 6

When does implantation occur?

Answer 6

day 7 after fertilization

Question 7

When does gastrulation occur?

Answer 7

during the week after implantation, and by day 15-16 gastrulation is complete

Question 8

What are the three primary layers formed in the gastrulation period?

Answer 8

endoderm, mesoderm, ectoderm

Question 9

What is the Mesoderm?

Answer 9

middle germ layer // circulatory and skeletal systems as well as serous membranes lining body cavities

Question 10

What is the Endoderm?

Answer 10

internal germ layer // forms lining of the gut and other internal organs

Question 11

What is the Ectoderm?

Answer 11

external germ layer // forms the skin, brain, nervous system, and other external tissues

Question 12

When does neural tube development occur?

Answer 12

begins during the third week and closes by the end of the fourth week

Question 13

What is happening in week 3 of gestation approx. ~17-18 days after fertilization for neural tube development?

Answer 13

approx. ~17-18 days after fertilization, neural plate forms and neural groove is first seen along midline of neural plate

Question 14

What is happening in week 3 of gestation approx. ~20 days after fertilization for neural tube development?

Answer 14

neural groove begins to thicken, elevate, and fold, eventionally becomes the neural crest

Question 15

What is happening in week 4 of gestation during neural tube development?

Answer 15

neural folds fuse to form the neural tube // leaves 2 openings at each end that are called neuropores, which eventually fuse a rostral neuropore and caudal neuropore

Question 16

What is happening at the end of week 4 of gestation in neural tube development?

Answer 16

it is completely fused by day 27

Question 17

What happens after neurulation is complete for the neural TUBE?

Answer 17

develops into the CNS central canal, represents future development of ventricular system

Question 18

What happens after neurulation is complete for the neural CREST?

Answer 18

After the neural crest has formed, it goes on to develop into the PNS

Question 19

What happens after neurulation is complete for the Ectoderm?

Answer 19

continues to develop into mammillary glands, hypophysis, subcutaneous glands, epidermis, hair, skin, nails, tooth enamel

Question 20

What are types of Neural Tube Defects?

Answer 20

Anencephaly, Encephalocele, Spina Bifida

Question 21

What is Anencephaly?

Answer 21

parts of the brain and skull fail to develop // failure of anterior or rostral neuropore fail to develop or fuse. not compatible with life. brain does not develop

Question 22

What is Encephalocele?

Answer 22

failure of skull to fully close, allowing brain and meninges to form a sac and protrude out of the skull // failure of anterior/rostral neuropore fusing. treated with surgery, neurologic defiits will persist w/ multiple surgeries depending on location

Question 23

What is Spina Bifida?

Answer 23

failure of vertebral column to fully close, allowing spinal cord and meninges to form a sac and protrude out of vertebral column

failure of posterior neuropore to develop and fuse

Question 24

What are the three types of Spina Bifida?

Answer 24

Spina bifida occulta, meningocele, meningomyelocele

Question 25

What is Spina Bifida Occulta?

Answer 25

failure of vertebral arch to fuse, bony defect, often not diagnosed until adulthood during xray

Question 26

What is Meningocele?

Answer 26

Meninges protrude through bony defect of vertebral arch, least common type, repaired with surgery usually during infancy

Question 27

What is Menigomyelocele?

Answer 27

spinal cord & meninges protrude through bony defect of vertebral arch // life long disabilities, leg weakness/paralysis, loss of bladder/bowel function

Question 28

What is also associated with a Menigomyelocele?

Answer 28

most infants with this also have Arnold-Chiari Type II malformation // brainstem/cerebellum is pulled through foramen magnum into upper spinal canal

Question 29

What is something that can help prevent neural tube defects?

Answer 29

Folic Acid (synethetic B9 Vitamin) / Folate (natural form of B9) during early pregnancy