SDL-4 Neuroembryology (1) Flashcards Preview

BB Test 1 > SDL-4 Neuroembryology (1) > Flashcards

Flashcards in SDL-4 Neuroembryology (1) Deck (60):
1

What does the ectoderm become?

 

Skin, sweat glands, hair, teeth, eye & ear, and pituitary

2

What does the mesoderm become?

Most organs, connective tissue, DURA MATER

3

What does the endoderm become?

Epithelial linings (GI, lung, bladder), parenchyma of 4 throat structures (Tonsils, Thyroid, paraThyroid, Thymus), liver and pancreas

4

Describe primary neuralation.

Induction of the ectoderm to form the neural plate until ectoderm fusion over neural tube

5

What genes are important in primary neurulation?

  • Sonic hedggehog (Shh)
  • FGF8
  • BMP4
  • TGFb

6

What is formed in primary neurulation?

C1-S2 segments

7

What are some defects associated with primary neurulation?

Craniorachischisis totalis, anencephaly, myeloschisis, encephalocele, myelomeningocele

8

What is Sonic hedgehog (Shh)?

  • Protein that induces overlying ectoderm to differentiate into neuroectoderm,
  • Signals for cell differentiation into VENTRAL spinal cord
    • Basal plate under influence of Shh
    • Opposes BMP gradient (promotes dorsoventral differntiation)

9

What is Bone Morphogenic Protein (BMP)?

  • Protein that signals for cell differentiation into DORSAL spinal cord
    • Alar plate under influence of BMPs
    • Opposes Shh gradient (promotes dorsoventral differntiation)

10

What are Homeobox genes (Hox genes)?

  • A set of genes that are variably expressed at different levels of the spinal cord and determines head-to-toe development
    • Important for anterior-posterior axis development and secondary neurulation

 

11

What is the cause of Craniorachischisis totalis?

  • Complete failure of neurulation - exposed tissue dies.
  • Incompatible with life

12

What is the cause of Myeloschisis?

Posterior neuropore not closed, neural plate caudal to NECK is open

13

What is the cause of Myelomeningocele?

Partial failure of posterior neuropore closure

14

What is dysjunction?

Separation of neural tube from surface ectoderm

15

Describe neural crest cells.

Transition from epithelial to mesenchymal, migrating away from neuroectoderm to mesoderm

16

What do neural crest cells become?

 

Nerve ganglia, autonomic ganglia, meninges, PNS glial/schwann cells (and connective tissues, melanocytes, & thyroid)

17

Describe secondary neurulation.

Mesenchymal cells around "posterior" neural tube (caudal mass region) form a tube and fuses with neural tube

18

What is formed in secondary neurulation?

S3-Coccyx innervations

19

What are some defects associated with secondary neurulation?

Diastematomyelia, tethered spinal cord, caudal regression syndrome

20

What is Tethered spinal cord?

Fixed caudal end of spinal cord (filum terminale anchors spinal cord, rendering it inflexible)

21

What is Diastematomyelia?

Split spinal cord due to persistence of neuroenteric canal

22

What is Caudal Regression Syndrome?

Sacral hypoplasia/hypoplasic femurs

23

What is Spina Bifida Meningocele?

Fluid-filled sac of meninges protrudes outwards

Neurological symptoms present

Spina Bifida Myelomeningocele (neural tissue included in fluid filled sac)

24

What is Spina Bifida Cystica?

Meninges or neural tissues protrude outwards

25

What is Spina Bifida Occulta?

Defective vertebral arches, asymptomatic (except little patch of hair over unclosed space)

Failure of sclerotome cells to migrate into the region dorsal to the neural tube leading to the absence of vertebral arches in that region

26

What are the layers of the neural tube?

  • Proliferative
  • Mantle
  • Marginal

27

Describe the proliferative layer of the neural tube.

Neuroepithelial cells, innermost of the layers, give rise to intrinsic cells of the CNS and ependymal cells along the spinal cord lumen (neurocele)

28

Describe the Mantle layer of the neural tube.

Neuroblasts, the "grey matter" of the spinal cord

29

Describe the Marginal layer of the neural tube.

Nerve fibers of neuroblasts, the "white matter" of the spinal cord

30

What is the sulcus limitans?

Groove between alar (dorsal) and basal (ventral) plates

31

What are primary vesicles?

Earliest differentiation (week 4) of the rostral neural tube

  • Prosencephalon (Forebrain)
  • Mesencephalon (Midbrain)
  • Rhombencephalon (Hindbrain)

32

What do primary vesicles become?

Forebrain, midbrain, hindbrain

33

What are secondary vesicles?

Week 6 differentiation of rostral neural tube

  • Prosencephalon (primary)
    • Diencephalon (secondary)
    • Telencephalon (secondary)
  • Mesencephalon (primary)
  • Rhombencephalon (primary)
    • Metencephalon (secondary)
    • Myelencephalon (secondary)

34

What are the flexures of the primary vesicles?

  • Cephalic
  • Cervical

35

What are the flexures of secondary vesicles?

 

Pontine

36

What do secondary vesicles become?

 

Diencephalon, telencephalon, mesencephalon, metencephalon, myelencephalon

37

What is the Prosencephalon?

Forebrain

38

What is the Mesencephalon?

Midbrain

39

What is this image?

Q image thumb

Mesencephalon

40

What is the Rhombencephalon?

Hindbrain

41

What does the Diencephalon become?

  • Thalamus/hypothalamus (two alar plates)
  • No basal motor plates

42

What is this image?

Q image thumb

Diencephalon

43

What does the Telencephalon become?

 

  • Cerebral hemispheres (lateral outpocketings)
  • Lamina terminalis (most rostral part of brain)

44

What is this image?

Q image thumb

Telencephalon

45

What does the Metencephalon become?

  • Pons
  • Cerebellum

46

What is this image?

Q image thumb

Metencephalon

47

What does the Myelencephalon become?

Medulla

48

What is this image?

Q image thumb

Myelencephalon

49

What is the casue of Holoprosencephaly?

Cerebral hemisphere fails to cleave

Ventral inductive defect (mutation in Shh)

Alcohol

Maternal diabetes

50

How does Holoprosencephaly present?

Malformation of brain and face, facial defects (i.e. cyclops eye)

51

What is the cause of Schizencephaly?

Failure of gyri to form in specific areas

Results in "Cleft Brain", cognitive impairment, paralysis, seizures

52

What is the cause of Lissencephaly?

Failure of gyri to form

Results in "Smooth Brain" (few gyri)

53

What is the cause of Pachygyri?

Failure of narrow gyri (fine-sized) gyri to form

Results in broad gyri, too few gyri

54

What is the cause of Polygyri?

Failure of broad gyri to form

Results in small gyri

55

What does the forebrain consist of?

Diencephalon (midline)

Telencephalon (lateral)

56

What is the organization of the Mesencephalon?

Basal plate (two functionally distint groups of motor nerurons):

  • Somatic efferent
  • General visceral efferent

Alar plate

  • Two sperate colliculi
  • Visual and auditory

Central canal

Marginal layer enlarges to form crus cerebri

57

What is the organization of the Myelencephalon?

Lateral walls everted

Alar plate (sensory groups; columns of neurons)

  • Somatic afferent (pain, touch, temp)
  • Special visceral afferent
  • General visceral afferent

Basal plate (motor groups; columns of neurons)

  • General visceral efferent
  • Special visceral efferent
  • Somatic efferent

58

What are risk factors for neural tube defects?

  • Alcoholism
  • Nutritional deficiency

59

How are neural tube defects diagnosed?

  • Ultrasound
  • Maternal alpha-fetal protein levels

60

What is Fibroblast Growth Factor (FGF)?

Protein secreted to maintain immaturity of neural progenitor cells, secreted from caudal mesoderm to form a caudal(high)-to-rostral(low) gradient (So, neural tube develops ROSTRAL TO CAUDAL)