The Problem of Distribution of a Nerve Growth Factor Specific for Spinal and Sympathetic Ganglia

Abstract

Enhancement of the nerve growth-promoting factor in mouse sarcomas by their passage as grafts in the chick embryo, as reported in the literature (8, 17), was confirmed with sarcomas MA387 and T241. No evidence for enhancement was observed with normal mouse tissues (Table 1). Low levels (1–2+) of growth-promoting activity were associated with cell-free derivatives from each of the following mouse tissues: kidney, thymus, spleen, placenta, heart, and voluntary muscles (Tables 2, 3). Lung and liver fractions were negative. The mouse submaxillary gland fractions were the most potent source and confirm the observations reported (4, 7, 12). Fractions from lumbosacral spinal ganglia, spinal cord, and the eviscerated-decapitated carcass of the 7- to 8-day chick embryo gave indications of having nerve growth-stimulating properties (Tables 2, 3). Similar fractions from the combined axial structures (spinal ganglia, spinal cord, somite derivatives, and notocord) produced maximum (3–4+) outgrowth. Protein fractions were prepared from mouse submaxillary glands and from axial structures of the 7- to 8-day chick embryo (Table 4). Traces of RNA and no DNA were found in these fractions. No decrease in the activity of the growth factor was observed after incubation with RNase or DNase. From these observations we concluded that the growth factor was associated with the protein component. No explanation can be offered at this time for the high levels of potency in the mouse submaxillary glands or the localization at lower levels of activity in axial structures of the 7- to 8-day chick embryo (Tables 3, 4). We tentatively submit the hypothesis that nerve growth-stimulating entities are fairly widespread in the tissues. Their succeessful demonstration will depend in each case on the development of adequate techniques.