Brain Development
115
Repellant
source
Attractant
source
Pioneer axon
Growth cone
Guidepost/stepping stone cells
Diffusible attractants
Diffusible repellants
Receptors for attractants
Receptors for attractant/receptor complex
Receptors for repellants
Eph/ephrins
Cell adhesion molecules
Lens
Retina
Tectum
EphrinB1/2
EphrinA2
EphrinA2
EphrinA5
EphrinA5
EphA3 EphA3
EphrinB1
EphB2/3
D
N
V
T
A
V
P
D
TAG-1
L1
Floor plate
Midline glia
Robo mRNA (+)
protein inactivated
by Comm
Robo mRNA (+)
protein activated
Wild
type
Robo-/-
Comm-/-
Slit
Slit
(a)
(b)
(c)
(d)
