Leucocyte morphology and chromosome morphology

The banding techniques currently employed in human cytogenetics for the identification of the individual chromosomes have been used to stain PHA lymphocytes and circulating leucocytes. The capacity of these techniques to localize singular chromosomes or chromosomal regions has been investigated. It has been observed that among the four major categories of bands (Q, G, E and R) only the quinacrine staining is informative in interphase nuclei, because of its peculiarity to stain the long arm of the Y chromosome and few other heterochromatic regions. Interphase nuclei treated according to the C bands show the presence of several heterochromatic masses, corresponding to the centromeric areas of individual chromosomes, but as such they cannot be recognized accurately. More specific and selective techniques, like G 11 and G Y protocols, appear to be suitable to localize the centromeric regions of chromosome no. 9 and the long arm of Y chromosome. Variation of the incubation time in the alkali saline solutions and of pH values have proven to be appropriate for the demonstration of other heterochromatic regions in interphase nuclei and in circulating leucocytes. The 'nuclear' approach to the study of specific heterochromatic regions of human chromosomes may be of practical interest into the investigation of several biological problems and into the detection of individuals carrying chromosome variants.