Free grafts of the common peroneal nerve of rats were performed, and the state of regeneration was observed at four week intervals the 24th post-operative week. The specimens used consisted of whole transverse sections of the nerve. These sections were magnified 2, 100X by electron microscope, and radom photogrphs were taken of 10 sites. The negatives were enlarged threefold to produce 6, 300X prints. Using the photos, the axon coordinates, diameters and peripheral lengths of the specimens were entered into a minicomputer (NOVA-01) that has an effective tablet area of 350 x 350 mm. with a Graf/Pen Model GP3 (Scientific Accessories Corporation). The computer programs were developed by the authors exclusively for this study. The axon spatial patterns were classified into three groups, those with regular, random and clustered distributions, respectively. Each of the 10 photographs of each section was tested to determine the category into which they fell. Two methods for analysis of the spatial patterns are available, The 'distance' method and the 'quadrat' method. We used both, but the results obtained by the former are presented in this report. It was noted that the sequence of spatial pattern changes in myelinated fibers during the regenerating process was clustered random, regular, thus gradually approaching the normal pattern.

Parts of this report were presented by Dr. Y. Miyamoto as an invited speaker at the WHO sponsored International Symposium on Posttraumatic Peripheral Nerve Regeneration held in Italy on October 16-18, 1980. A considerable amount of additional data has been used in the completion of this manuscript.

Part of the research funds for this work was made available by a Project Research Grant (#55-405, #55-001) from Kawasaki Medical School.