A method to correct adequately for the change in neuronal size when estimating neuronal numbers after nerve growth factor treatment.

A method is described to compute the correct distribution of nuclear diameters in thick sections of superior cervical ganglia of rats from the observed distribution of nuclear profiles. This method is applicable to the problem of correcting for the differing diameters of cells observed after treatment with nerve growth factor (NGF). It overcomes the errors due to the failure to count small fragments of nuclei too thin to be seen and the multiple counting of nuclei in more than one section. It has been shown that the changes in number of neurons after NGF treatment were not as large as previously supposed. An estimate of the volume occupied by the cell bodies suggests that the numbers calculated here are correct.