ASPECTS OF THE QUANTITATIVE-ANALYSIS OF NEURONS IN THE CEREBRAL-CORTEX

We address three problems concerning the quantitative analysis of nerv e cell distribution in the cerebral cortex: (i) preparatory tissue def ormation (shrinkage); (ii) difficulties in differentiating between sma ll neurons and astroglia; and (iii) the bias introduced by the countin g method. We found that staining with Richardson's solution led to no shrinkage in Vibratome-cut sections of aldehyde-fixed rat brains, but did result in staining of the neurons and left the glial cells unstain ed. This was in striking contrast to Nissl staining which introduced a linear shrinkage of 20-30% and stained all kinds of cortical cells in discriminately. A computer-based unbiased counting method was implemen ted by taking advantage of the stereological procedure referred to as the 'optical disector' (Gundersen, H.J.G. (1986) Stereology of arbitra ry particles, J. Microsc., 143: 3-45).