Morphometric analysis of the inferior olivary complex in infants and adults

In the literature, few studies detailed morphometric parameters of the inferior olivary complex, and mainly applying biased methods based on counting in a two-dimensional plane. In the present work, the unbiased quantitative method of the optic disector was applied in order to analyse neuronal densities, nuclear volumes and total neuron numbers of the principal (PION), medial (MION) and dorsal (DION) nuclei of the inferior olivary complex in adults (16 male, 6 female; mean age: 37 years) and infants (5 male, 5 female; mean age: 5 months). In both adult and infant series, statistically significant differences were not found in neuronal densities between the various inferior olivary nuclei. All the nuclei showed higher volumes and lower neuronal densities in adults than infants, without statistically significant differences in total neuron numbers, thus suggesting postnatal development of the neuropil.