Fiber analysis of an insect peripheral nerve: Light vs. electron microscopy

This paper describes the morphology of one of the two major femoral nerve trunks (nerve V of Dresden and Nijenhuis (1958)) of the cockroach Blaberus discoidalis as revealed by light microscopy, scanning electron microscopy and transmission electron microscopy. Fiber analysis of light and electron micrographs of thick and thin sections taken from adjacent areas of the same nerve yield significantly different data about the number and size distribution of the component axons of nerve V. The light microscopic image indicates one example of nerve V contains 2030 individual axons with a mean diameter of 1.4 μ; the electron image indicates the nerve contains 5794 axons with a mean diameter of 0.56 μ. The disparity between the two types of data is due to the large number of very small axons (0.2 μ or less in diameter) that course through the femoral nerve.