Fig. 3.

Position-dependent preferential outgrowth of spinal neurites on membranes from individual muscles. Spinal cord slices cut from the cervical (rostral, RSC) or lumbar (caudal, CSC) enlargement were placed on alternating stripes of membrane derived from the serratus anterior (S), a rostral muscle, or from the gluteus (G), a caudal muscle. Membranes applied to one set of lanes in each culture were mixed with fluorescent beads to mark lane boundaries. After 3 d, the cultures were fixed, and neurites were labeled with antibodies to neurofilaments. (Figures shown are unstained.) A, Rostral spinal cord neurites grew selectively on serratus anterior membranes in 36% of cultures. B, Caudal neurites grew selectively on gluteus membranes in 47% of cultures. Magnification: A, 100×; B, 80×.