INFLUENCE OF TARGET TISSUES ON THEIR INNERVATION IN OLD-AGE - A TRANSPLANTATION STUDY

AGE-RELATED changes in the nervous system might be intrinsic to the neurons or secondary to changes in the target tissues they supply. We have investigated this question by transplanting old and young vascular muscle into contact with young host nerves in oculo and observing the reinnervating nerve fibres. The density and pattern of reinnervation were those typical of the age of the target tissue, thus old transplants imposed an 'old' pattern of reinnervation on young host nerves. Our findings strongly support the hypothesis that target tissues determine the pattern and density of their innervation in old age.