Neural development 2

Question 1

Anterior-posterior polarity of neural tube

Answer 1

Neural tube formation begins in middle at embryonic day 20
Openings at each end are anterior (cranial) and posterior (caudal) neuropores
Anterior closes on day 25, posterior on day 27

Question 2

Somites

Answer 2

Balls of mesoderm that mature into segmented axial skeleton

Each pair added sequentially from head to tail down length of embryo

Question 3

Wnt signalling

Answer 3

Controls anterior-posterior development of nervous system

Wnt inhibitors (Dickkopf, cerberus, Frzb) are mae by dorsal anterior mesoderm and organiser

Question 4

FGF and RA

Answer 4

FGF made at posterior and degraded at anterior
RA made by central mesoderm
FGF, RA and Wnt all regulate Hox gene expression
Unique cocktail of Hox at each segment specifies its anterior-posterior identity

Question 5

Brain development from neural tube

Answer 5

Anterior divides to form three primary vesicles (forebrain, midbrain and hind brain)
Part of forebrain curls up and around (will become cerebral cortex)
Posterior part forms spinal chord

Question 6

Neuron migration

Answer 6

Immature neurons migrate on radial glial cell processes to final positions

Question 7

Cortical layers

Answer 7

First cohort of post-mitotic neurons moves from ventricular zone and forms preplate
First migration wave of cortical plate (CP) neurons arrives at middle of PP and splits into three zones (marginal zone, cortical plate and subplate)
More CP neurons arrive in an inside out sequence

Question 8

Visualising neurons

Answer 8

Neural cells express nestin during early CNS and PNS development (can be immunostained)
Immature glial cells express vimentin
Mature nerve ells express neurofilament proteins

Question 9

Reelin

Answer 9

Extracellular matrix-associated glycoprotein
Important for cortical development
Reelin gene RELN mutation linked to lack of brain folds (lissencephaly) and autism