Lecture 9 - Neurulation and the Formation of Axial Structures

Question 1

period of development starting with the first traces of formation of the neural plate and ending with the closure of the neural tube

Answer 1

neurulation

Question 2

process of neurulation

Answer 2

1. primary inductive event
2. action of chordamesoderm or notochord on overlying ectoderm
3. result into transformation of unspecialized ectodermal cells into the primordium of the CNS

Question 3

initial response in neurulation

Answer 3

1. induced ectoderm
2. form a plate of thickened cells
3. transform into a groove
4. folds up into a tube

Question 4

segmentally arranged aggregations which other ectodermal cells from the junction between the neural and general cutaneous ectodermal tissues form

Answer 4

neural crest

Question 5

symmetrical pairs of brick-like masses that is formed by blocks of mesoderm on either side of notochord

Answer 5

somites

Question 6

where do somites first take shape

Answer 6

near cranial part of the embryo

Question 7

gradient which the differentiation of axial structures follow

Answer 7

cephalocaudal gradient

Question 8

involuting around the dorsal lip of blastopore in amphibians

Answer 8

chordamesoderm

Question 9

forms from cells passing through Hensen’s node in birds and mammals

Answer 9

notochord

Question 10

chordal cells induce overlying ectodermal cells to thicken, forming what

Answer 10

neural plate

Question 11

anterior inducer

Answer 11

• noggin
• chordin

Question 12

posterior inducer

Answer 12

• FGF-8
• middle

Question 13

initiates the formation of CNS and causes the central longitudinal axis of the body to be established

Answer 13

neural induction

Question 14

inductor in neural induction

Answer 14

chordamesoderm

Question 15

responding tissue in neural induction

Answer 15

ectoderm

Question 16

components of neural induction by Gilbert & Saxen in 1993

Answer 16

1. inductive signal itself
2. acquisition of competence of the dorsal ectoderm to respond to inductive signals
3. regional specification of the induced neural plate into craniocaudal regions from brain to spinal cord

Question 17

protein that is capable of converting ectoderm to neural ectoderm

Answer 17

noggin

Question 18

neural induction is associated with increase activity of what

Answer 18

protein kinase C α in dorsal ectoderm

Question 19

cluster of cells that release diffusable signal molecules, which convey positional information to other cells

Answer 19

organizer

Question 20

signal molecule

Answer 20

morphogen

Question 21

when does the creation of the Spemann organizer start

Answer 21

oogeneis in the mother

Question 22

function of Spemann organizer

Answer 22

dorsal mesoderm development is a result of the inhibition of ventral development

Question 23

functions like a Spemann’s organizer in chicks

Answer 23

Hensen’s node

Question 24

induction that occurs between the three primary germ layers

Answer 24

primary induction

Question 25

induction that occurs between tissues that have already been specified to develop along a particular pathway

Answer 25

secondary induction

Question 26

ex of primary induction

Answer 26

differentiation of the central nervous system during neurulation

Question 27

ex of secondary induction

Answer 27

development of the lends of the vertebrate eye

Question 28

regional categories of induction

Answer 28

1. archencephalic induction 2. deuterencephalic induction 2. spinocaudal induction

Question 29

anterior head

Answer 29

archencephalic induction

Question 30

posterior head

Answer 30

deuterencephalic induction

Question 31

trunk and tail

Answer 31

spinocaudal induction

Question 32

Two stages of neural induction

Answer 32

1. neural transformation (evocation) 2. regional specification

Question 33

Four stages of neural tube formation

Answer 33

1. thickening of neural plate 2. establishing contours of the neural plate: cell shape changes and rearragnement of cells 3. lateral neural folds elevate to form the neural groove 4. apposition and fusion of neural folds to form neural tube

Question 34

ectodermal cells population that separate from the forming neural tube

Answer 34

neural crest

Question 35

unclosed anterior and posterior open ends of neural tube

Answer 35

neurospores

Question 36

3 primary brain vesicles

Answer 36

1. forebrain (prosencephalon) 2. midbrain (mesencephalon) 3. hindbrain (rhombencephalon)

Question 37

5 secondary vesicles the three brain vesicle differentiate into

Answer 37

1. telencephalon 2. diencephalon 3. mesencephalon 4. metencephalon 5. myelencephalon

Question 38

tissues which consist of aggregates of spindle-shaped or stellate cells embedded in intercellular matrix

Answer 38

mesenchyme

Question 39

where does mesoderm in chick embryo originate

Answer 39

from epithelial epiblast layer

Question 40

fate of chordamesoderm

Answer 40

notochord

Question 41

fate of intermediate mesoderm

Answer 41

- kidneys - gonads

Question 42

fate of lateral plate mesoderm

Answer 42

- circulatory system - linings of body cavity - extra-embryonic

Question 43

fate of apraxoal mesoderm

Answer 43

- head - somite

Question 44

fate of somite

Answer 44

- cartilage - skeletal muscle - dermis

Question 45

mesoderm sheets on either side of notochord which separate into rounded regions

Answer 45

somitomeres

Question 46

somitomerse that separate into segmented blocks

Answer 46

somites