Split Nucleoli as A Source of Error in Nerve Cell Counts

Abstract

The number of nerve cells in a given ganglion or nucleus is usually determined by counting the nucleoli in serial sections. The possibility that nucleoli may split and appear in more than one section is recognized as a source of error. A determination of the value of this error was made as follows; from nodose ganglia of four cats were cut serial transverse sections in which the sections varied in thickness. Thus from one ganglion, four sections were cut at 12 μ, then six at 9μ, and eight at 6μ. The process was repeated over and over until the entire ganglion was sectioned. The other ganglia were sectioned similarly. After mounting and staining, separate counts were made of the nucleoli of each given ganglion from the sections of different thicknesses. If nucleoli split according to theoretical expectations, the percentage of nucleoli split in thick sections should be less than the percentage split in thinner sections and the counts based on the sections of different thicknesses should vary accordingly. The results obtained indicate that the counts from thin sections do not differ appreciably from counts from much thicker sections, i. e., the thickness of the sections does not affect the count. It is, therefore, concluded that no correction should be made for split nucleoli if the sections are around 10 μ in thickness and none but distinct and definite nucleoli are counted.