Energy metabolism in spinal motoneurons of the zebrafish.

Enzyme histochemical profiles of the energy metabolism in spinal motoneurons of fish, ranging in length from 18 mm to 53 mm, were investigated. Energy is used for ion pumps to maintain the resting membrane potential and for other processes of which transport and biosynthesis may be the most important. In this paper particular attention is paid to the impact of biosynthesis on the energy metabolism in motoneurons. As the innervation ratio of fish motoneurons increases dramatically during growth, we suppose that the formation and maintenance of functional connections with the target muscle accounts for the high level of the energy metabolism in motoneurons.