A glycoprotein portion of the laminin binds with a glycosyltransferase on growth cones. See Plate 20 for a colored picture of this. G adheres to P1 and P2 axons and grows anteriorly. Membranes isolated from the cell surfaces of the posterior half of the somite in chicks cause collapse of DRG neuron growth cones. A glycoprotein isolated from chick somites causes collapse of growth cones.
Axons grow into the limb buds before any recognizable structures are present.
Axons from motor neurons are repulsed by ventral sclerotome, and the sclerotome cells are loosely organized. Motor neuron growth cones are also repulsed by tissue that will form the pelvic girdle. Motor axons were in a different position, but found their way back to the correct muscles if they wre able to locate the correct plexus.