Lecture 11 objective 1

Question 1

Thickening

Answer 1

Overlaying ectoderm thickens, columnerize, involves microtubules

Question 2

Shaping

Answer 2

convergent extension = ectodermal cells forming neural plate migrate toward midline, become longer along anterior-posterior axis

Question 3

Folding

Answer 3

median hinge point created by actin, induced by notochord

columnar cells —> pyramidal cells
Lateral hinge point emerges
elevation of neural folds: due to pushing inward by expanding non-nerual epithelium

Question 4

Neutral tube formation

Answer 4

due to fusion of apical surfaces of neural folds

mediated by glycoconjugates

begins midway along neural tube (21-22 days)

Extends cranially and caudally

anterior/posterior neuropores at day 23

Question 5

When are anterior/posterior neuropores formed?

Answer 5

23 days

Question 6

4 stage time line: 18, 20, 22, 23

provide structures as they appear

Answer 6

18 days

neural plate, fold, streak

20 days

all of that + neural groove + somites + neural plate

22 days

midline fusion

23 days

anterior/posterior neuropores

somites