Quantitative and cytometric analysis of the ventral cochlear nucleus in man

A systematic quantitative and cytometric study of the ventral cochlear nucleus has been performed on 3 groups of histologically normal brains, ranging in age from 20 weeks of gestation to adult life. Serial sections, 20 micrometer in thickness, through the length of the nucleus were obtained from paraffin-embedded blocks of the ponto-medullary junction. Every 10th section was analyzed with a Cambridge Imanco Quantimet 720 Image Analyzing system. The surface area of the nucleus was determined on each slide. Cells showing neuronal characteristics were individually counted and classified into 18 pre-determined cell size classes. The raw total number of cells was then corrected for periodicity and split cell error. The total volume of the nucleus and cell packing density were estimated. The mean total number of neurons was 26,098 in premature, 31,802 in full term and 30,440 in adult cases. There was no significant difference among these values. The mean volume of the nucleus was 1.32 mm3 in premature, 3.84 in full term and 5.43 in adult cases. Positive correlation coefficients were found comparing volume versus age. A negative correlation coefficient was detected comparing cell packing density versus age from the full term period to adult life. A significant increase in the number of cells in the largest cell classes was also found with increasing age. The mean neuronal diameter did not change significantly between premature and full term cases but was significantly different between full term and adult cases. These findings are discussed and compared to already reported quantitative studies of the ventral cochlear nucleus in man, which involved manual counting techniques.