COM 2 Histology

Question 1

What week does the nervous system first start to develop

Answer 1

• week 3

Question 2

What are the first signs of the nervous system development

Answer 2

• Apperance of the neural plate and neural groove

Question 3

What stimuates the ectoderm /induces it + name the the 3 key signalining molecules included

Answer 3

• Notochord and paraxial mesenchyme
  Key signaling molecules:
  -TGF-b family, Sonic hedgehog(SHH), BMPs

Question 4

When does neurulation sart+ what region

Answer 4

Week 4 in the region of the 4th - 6th somites

Question 5

What does the cranial 2/3 of the neural plate/tube form + the cranial 1/3

Answer 5

Cranial 2/3 of the neural plate forms the future brain
Cranial 1/3 forms the future spinal cors

Question 6

What does the neural tube develop into

Answer 6

• CNS

Question 7

What does neural crest give rise to

Answer 7

Most of the PNS and ANS

Question 8

When does neural tube closure begin

Answer 8

At the 5th somite

Question 9

What day does the rostral(cranial) neurpore + the caudal neuropore close

Answer 9

• Rostral(cranial) neuropore closes around day 25
  -Caudal neuropore closes around day 27

Question 10

What does the neural canal become

Answer 10

• Ventricular system of the brain and central canal of the spinal cord

Question 11

Name the 2 key proteins involved in neural tube closure

Answer 11

• SDC4,syndecan 4
• VANGL2, van gogh- like 2

Question 12

What do neuroprogenitor cells thicken

Answer 12

Neural tube wall to form the brain and spinal cord

Question 13

What does the spinal cord develop from

Answer 13

• Caudal part of the neural plate and caudal eminence

Question 14

What is crucial for spinal cord development

Answer 14

• Retinoic acid signaling

Question 15

What is the ventriuclar zone(ependymal layer, part of the spinal cord)- COMPOSED of

Answer 15

• Pseudostratified neuroepithelial cells

Question 16

What does the Ventricular zone(ependymal layer) give rise to + wht they contents turn into

Answer 16

• Neurobalsts - form intermediat zone(mantle layer) , then become grey mater
• Gioblasts- differentiate into astroctyes and oligodendorcytes
• Ependymal cells
  -Marginal zone

Question 17

What does the marginal zone form + it becomes white matter as the axons grow from what

Answer 17

The outer neuroepithelial cell
- As the axons grow from :
-Spinal cord neurons
-Spinal ganglia
-BrainW

Question 18

What is microglia derived form

Answer 18

• Mesenchymal cells

Question 19

When does the microglia enter the CNS

Answer 19

aFTER invasion

Question 20

What does the microglia functions as part og

Answer 20

• mononuclear phagocytic cells

Question 21

What does does the Sulcus Limitans divide the spinal cord into

Answer 21

• Alar plate (Dorsal)
  -Basal plate( Ventral)

Question 22

What does the Alar + basal plate( formed from sulucs limitans ) FORM

Answer 22

• Alar plate :Dorsal gray columns/ horns
• Basal plate: Forms the ventral and lateral gray columns/horns

Question 23

How does the Axons of the ventral horn cells grow and what do they from

Answer 23

They grow outwards, form the ventral roots of the spinal nerves

Question 24

What do most spinal cord defects result from

Answer 24

• Failure of neural arch fusion during the 4 th weel

Question 25

What is the name of the mild form of Spina bifida

Answer 25

- Spina Bifida Occulta

Question 26

What is spina bifida occulta caused by

Answer 26

- Nonfusion of verteberal arches

Question 28

What do most spinal cord birth defects result from

Answer 28

- Failure of neural arch fusion during 4th week of development

Question 29

What is the name of the mild form of spina bifida

Answer 29

- Spina Bifida occulta

Question 30

What is spina bifida occulta caused by

Answer 30

Nonfusion of vertberal arches

Question 31

What is the name of the severe form of spina bifida

Answer 31

- Spina Bifida cystica

Question 32

What are the subtypes of Spina Bifida cystica+ what protudes in each

Answer 32

- Meningocele - Meninges and CSF protude -Meningomyelocele- Meninges + spinal cord protude

Question 33

What may spinia bifida occulta be present as

Answer 33

- birthmark, lipoma, dimple

Question 34

What is spina bifida cystica characterised by

Answer 34

- Protrusions of meninges and spinal cord

Question 34

What is meroencephaly

Answer 34

Severe neura defect

Question 35

What are symptoms of meroencephaly

Answer 35

Absence of skullcap Facial abnormalities+ brain abnormalities

Question 36

How is meroencephaly( severe neural defect) diagnosed

Answer 36

- High levels of alpha fetoprotein(AFP) in amniotic fluid OR MATERNAL SERUM

Question 37

In relation to neural defects, what can ultrsound detect

Answer 37

- Vertebral defects -Protruding meningeal cysts