Morphometric analysis of neurons in ganglia: geniculate, submandibular, cervical spinal and superior cervical.

The geniculate ganglia (GG), the submandibular ganglion (SG), the cervical spinal ganglion (CSG) and the superior cervical ganglion (SCG) are clinically important. But details of these ganglia have not been included in textbook descriptions. We conducted research to bring precise figures to light. We prepared serial sections of these ganglia in five Japanese adults after precise dissections to count the numbers, measure the perimeters and the areas, and calculate the circularity ratios (CRs) of the ganglion cells. The numbers of neurons were in the following order: SCG > CSG > SG > GG, and the average neuronal areas in the following order: CSG > GG > SG > SCG. Average neuronal CRs were around 0.90 in all ganglia. In other words, the morphometric evaluation showed that neurons in such ganglia are practically circular in shape. Our morphometry thus reveals that the neurons in these ganglia are sensory neurons in the broad definition of the word from a quantitative point of view.