The effects of nerve growth factor on the spinal ganglia of Ambystoma maculatum.

Abstract

AbstractNerve growth factor (NGF) isolated from mouse submaxillary glands was injected three times weekly into late embryos and young larvae of Ambystoma maculatum for a period of three weeks, producing an enlargement of the spinal ganglia owing to hyperplasia. This hyperplasia corresponds to the method of normal growth of ganglia at this late embryonic period of development, which is similarly one of cell multiplication rather than cell enlargement. The response of animals kept in the cold (12°C) during the experimental period, and which had reached Harrison stage 41 by the end of the experiment, was of doubtful significance, contrasted with that of animals maintained at room temperature and which had become 15 mm larvae by the end of the experiment. The latter group showed an increase in ganglion size of 100% over controls. The difference in magnitude of response of the two groups is believed to be due to the existence of a limited period in development when the animal is sensitive to NGF. The slowly developing animals in the cold had probably just reached the sensitive period by the end of the experiment, thus accounting for their small response compared with that of the animals which were allowed to develop further.