Stability of large cell-medium cell clusters in the mature neostriatum.

Large neurons of the mouse caudate nucleus contain profuse Nissl material, have a maximal pole-to-pole diameter of up to 25 micron, occur preferentially within a central or CORE zone of the neostriatum, and are almost always located within territories delimited by medium-sized clustered neurons. Examination of coronal sections taken through the head of the nucleus and stained with cresyl violet revealed the absence of age-related pathology as evaluated by three parameters: (1) there was no statistically significant difference in the frequency of large neurons in all areas of the head of the nucleus; (2) the large neuron continued to be confined preferentially to the CORE zone of the head of the nucleus throughout the time period studied; and (3) no statistically significant shifts were detected in the geometry of large cell-medium cell clusters. Since postnatal age did not significantly affect the frequency, distribution or geometry of large cell-medium cell clusters, data from all animals was combined. This information was used to evaluate the possibility of an interaction between location within or outside the CORE zone and type of large cell-medium cell cluster, but these results were not statistically significant. Therefore, the data analyzed in this study support the view that the geometry of large cell-medium cell clusters is extremely stable in the mouse neostriatum and seems not to be influenced either by age of the animal or by location of the cell grouping.