A simple method for staining of nucleoproteide equivalents in human FL cell chromosomes

Chick embryo cell monolayers (CEC) treated by acidified thiazine dyes (pH 5 to 3) arrived into a mitogenic state. The diffuse dispersed chromatin of the nuclei clustered on the nuclear membranes and on the nucleoli in chromosome-like figures is usually estimated by electron microscopy. The clustering process could better be followed by light microscopy. The same treatment with acidified thiazine dyes on Fogh and Lund (FL) cell monolayers led unequivocally to induction of pre-formed chromosomes in interphasic cells with the same location as in the CEC. On the other hand, in metaphasic nuclei of FL cells, the above stain showed a cluster of deeply stained granules and pale stained strings. The last cluster model could be observed in the interior of metaphasic chromosomes aligned along the chromosomal arms in longitudinal, horizontal and/or crisscross position. These cluster patterns differ from conventional chromosomal bands obtained by Giemsa of fluorescent staining.