Proliferative index estimated by chromatin pattern analysis.

Chromatin pattern analysis at different density thresholds in Feulgen-stained meristems stimulated to proliferate by water inbibition, allows to estimate a proliferative potential index (PPI) which is a much earlier indicator of changes in proliferation than conventional labelling and mitotic indices. The PPI is but the ratio G1 cells to total 2C cells (or G2 to 4C cells, when cells also digress from the post-replicative stage of the cycle). The method is based in the fact that G1 and G2 cells have larger projected nuclear area and smaller dense chromatin area than their conterpart non-proliferating G0 and G0,2 cells.