Enzyme-histochemical studies of "retrograde" reaction in motor neurones of immature rats.

Changes in immature rats in motor neurones after axotomy were studied by enzyme-histochemical methods. Increased activity of dehydrogenases in these neurones demonstrates enhanced metabolism and there was also increase of acid phosphatases. Decreased activity of acetylcholinesterase and indoxylacetate esterase in the neurones and their processes seems to indicate impaired neuronal function to transmit impulses. "Retrograde" reaction in the immature and the grown up animal is in general of the same kind but takes place quicker in the immature rat. However, in new-born and very young animals, it is difficult to recognize alterations in the anterior horn of the spinal cord. Therefore, nervous tissue of new-born animals seems not to respond as it does some days later in ontogenesis.