Nerve Growth Factors and a Thymus Inhibitor, Separation by Tissue Culture on Acrylamide Gel

Abstract

EXTRACTS of the submaxillary gland of male mice induce hyperplasia of sensory and sympathetic ganglia in chick embryos; the effect can be duplicated on explants of sensory ganglia in vitro^1,2. When injected into newborn mice, the same extracts lead also to runting, retardation of coat development and sundry abnormalities of growth^1,3. Because such varied effects are unlikely to be caused by a single substance, we sought to isolate and to assay separately the effective components of salivary glands. To this end the extracts were stacked and run on acrylamide gels (L. Ornstein and B. J. Davies, personal communication), and a method was developed whereby target cells could be cultured directly on these gels. The presence of several growth regulating substances has thus been recognized: two distinct bands of “nerve growth factor”, one band containing an inhibitor of nerve growth, and one band causing inhibition and lysis of thymic cells.