Method for the determination of mean densitometric profiles of chromosomes: application to human chromosomes stained by quinacrine mustard, ethidium bromide or by the Feulgen reaction.

When comparing the densitometric profiles of corresponding chromosomes registered from different metaphases or homologous pairs, one is always faced with the variability of their length and overall height. This makes difficult the quantitative comparison of a given chromosome treated by various staining procedures.--A simple and rapid method has been developed for normalizing the densitometric profiles and averaging them in order to obtain a "mean density pattern" of each chromosome. The analysis involves: photographic images, digitalization of the densitometric profiles and processing of the data by a mini-computer.--The method, based on a linear relationship between the area of the densitometric profiles and their length, has been applied to five human chromosomes (1, 2, 6, 12 and 16) stained by ethidium bromide, quinacrine mustard (with or without acidic hydrolysis), pararosaniline and bisaminophenyl-oxadiazole (Feulgen reaction).