METABOLIC CHANGES IN AXOTOMIZED FETAL AND EARLY POSTNATAL HAMSTER FACIAL MOTONEURONS - AN AUTORADIOGRAPHIC STUDY

The developing facial neurons of a series of hamsters ranging in age f rom the 14-day fetus to the 9 day postnatal were axotomized. Postopera tive times were graded for each age so that the retrograde response co uld be observed before any significant amount of cell degeneration or death occurred. The incorporation of tritiated uridine was followed by the autoradiographic procedure. Although grain counts, relative to co ntrol values, were significantly reduced only in the axotomized fetus and at 24 hours postoperatively in 4-day postnatal animals, there was also a repression of isotopic incorporation in all the other axotomize d animals. These results support data obtained from previous work with the hamsters which indicate that it is not until after the nerve cell nucleolus reaches full cytomorphic maturity (between 15 and 20 days p ostnatal age in hamster facial neurons) that the axotomized neurons re spond with significantly increased incorporation levels of isotope ove r that of control neurons.