Stimulation of choline acetyltransferase in spinal cord explants by limb mesenchyme.

Choline acetyltransferase (ChAT) activity in developing spinal cord explants in vitro is shown to be dependent on the presence of co-cultured immature limb tissue. Frog tadpole spinal cord explants grown on collagen or polylysine expressed stage-appropriate levels of ChAT activity only when in the presence of the limb mesenchyme target. Neither skeletal muscle nor polylysine, both of which enhance neurite growth accompanied by increases in cord protein, were capable of maintaining the level of ChAT activity characteristic of these spinal cords in vivo. The results demonstrate that developmentally significant levels of ChAT can be maintained in vitro under appropriate conditions that may act in part through the maintenance of cholinergic motor neurons.