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Flashcards in Embryo Deck (30):
1

what are 2 mechs. creating a neural tube

1. primary neurulation - primary neurla tube from neuroectoderm and nerual plate
2. secondary neurolation - secondary tube from mesoderm left from primitive stalk

2

what are 2 main steps to primary neurulation

1. induction of neuroectoderm from neural plate
2. elevation apposition, contact and fusion of the folds

3

what organizes neuroectoderm

notochord

4

where does closure begin

in what will be cervical and goes rostral and caudal

5

what are ends where fusion occurs called

rostral and caudal neuropores

6

what happens at the caudal end of neural closure

medullary cord condense and tube extends into it and undergoes mesenchymal condensation

7

what does this caudal neurulation form?

the sacrum

8

what is freq. of neural tube defects

1:1000

9

what are risk factors for defects

Hx of defects, diabetes, obesisty, anticonvulsant meds --- most women have none

10

what lowers risk

folic acid

11

what is unclosed rostral pore

anencephaly

12

what is arnold chiari malformation

posterior cransial fossa too small and foramen of mygandi compressed to get hydrocephalus

13

what are 2 ultrasound signs of spina bifida

lemon sign - flattening of frontal bone
banana sign - curved contour of cerebellum

14

what are 2 steps of shaping the neural tube

1. dev. of brain vesicles
2. dev. of brain flexures

15

what are primary vesicles (3)

1. proencephalon
2. mesencephalon
3. rhombencephalon

16

what are secondary vesicles and what will they become (5)

1. telencephalon - hemispheres
2. diencephalon
3. mesencephalon - midbrain
4. metencephalon - pons and cerebellum
5. myencephalon - medulla

17

what are the 3 flexures

1. midbrain flexure
2. cervical flexure
3. pontine flexure

18

what forms intermediate zone

migration of neurobalst and glioblasts toward outer wall (will be grey matter)

19

what forms marginal zone

extension of neuroblasts even further out (will form white matter)

20

what happens to cells that remain adjacent to neural tube

ependymal cells

21

what are layers of tube from in to out

ventricular>intermediate>marginal

22

how is grey matter established in cortex

radial glial cells extend out into margins and primitive neuroblasts migrate along them

23

what are dorsal and ventral thickening of intermediate zones

1. dorsal - alar plates
2. ventral - basal plates

24

what do these plates become

1. alar plates - interneurons
2. basal plates - motor neurons

25

what signalling proteins are used to differentiate floor from roof

floor releases SHH - basal plates
roof releases BMP -alar plates

26

what causes the outward flaring of alar plates at the medulla and pons

the pontine flexure

27

what are 2 consequences of the faster growth of the vert than the cord

1. dissociation of the cord from vert. segments
2. cauda equina

28

what 2 things is PNS developed from

1. neural tube
2. neural crest

29

what does the tube contribute to

1. lower motor neurons
2. preganglionic autonomic neurons

30

what do the crest cells become

1. dorsal root ganglia
2. post-ganglionic neurons of autonomic system

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