The relationship between internodal length and fibre diameter in the spinal cord of the cat.

The relationship between internodal length and external fibre diameter in the spinal cord was examined on glutaraldehyde perfused material from a number of cats. The relationship in all samples was highly significant and there was no significant difference either between animals or between the lateral and dorsal columns. However, there was considerable variability, some internodes being twice and others less than half as long as the length predicted by the regression equation. Our results showed that the relationship between internodal length and fibre diameter was essentially a linear function. No internodes shorter than 100 micrometers were seen.