Abstract
There are only a little morphometric data analysing the age-related changes of human nerve fibers. In the present study a new staining method that permits simultaneous observation of the axon and the surrounding myelin sheath was used to study the morphometric changes which occur in the human nerve fibers during the aging process. The following combination of equipment was employed in this study : an image-analyzing digitizer, a microscope with a drawing tube and a computer for data storage and statistical analysis. The numbers and transverse areas of axons were measured in 5 human maxillary nerves. The average number, the average area, the total area, the average perimeter and the total perimeter of axons decreased from 50 to 90 years of age ; in particular, a dramatic changes occurred from 80-90 years of age. Under microscopic observation, the maxillary nerves in a 95-year-old specimen consisted chiefly of relatively small axons (Fig. 2) compared to those of a 59-year-old specimen (Fig. 1) . A significant reverse correlation was observed between the various age groups and the five items listed above. Our results deduce that definite changes occur in the maxillary nerves with aging.
