[The validity of measuring methods for intranuclear DNA on thin sections. Theoretical and experimental study]

Computer modelling is used to simulate nuclear segments obtained by random sectioning through tissue. A few more computations lead to DNA measurement simulation. Simulation results in negatively skewed DNA frequency distributions. Both the right skewness and the coefficient of variation of measurements are increasing with the ploidy level because nuclear DNA content is assumed to be related to nuclear size in the chosen model. Observed mean values are biased underestimates of expected values but are strongly correlated to the degree of ploidy. Finally, the bias introduced by measuring nuclear segments instead of whole nuclei increases the variance of measurements but contributes to less than half the experimentally observed variance. Our conclusion is that microspectrophotometry on tissue sections is a valuable method for DNA content evaluation of small clusters of pathological cells as one may find in endoscopic biopsies.