Growth regulator from spinal cord: produced in cultures of glial cells

Spinal cord cultures produced a regulatory factor which inhibited myogenesis. After serial passage (x 3) production of this factor continued as neuronal cells disappeared and large, pale polygonal cells rich in cytoplasmic microfilaments with morphology of astrocyte precursors became predominant. These glial cells responded to dibutyryl cyclic AMP by assuming a star-shaped appearance with multiple, radiating cytoplasmic processes. Cultures active in production of the growth regulator also produced nonneuronal-type enolase and glutamine synthetase. It is suggested that the growth regulator is produced by astrocytic glia in culture.