Romanowsky staining of suspension-fixed lymphocytes and fibroblasts, deposited as monolayers on slides, involves an initial basic dyeing process followed by formation of a hydrophobic Azur B/Eosin Y complex at the more permeable and so faster staining cellular sites. This mechanism is shared with blood and marrow smears. However certain morphological features peculiar to suspension-fixed, cell culture-derived preparations also influence the staining pattern via rate control: namely the irregular and bulky profiles of flbroblasts, compared to the smoother and thinner lymphocytes; and the occasional superficial occlusion of cells by culture medium.
In the present study we hoped to gain insight into these disagreements by altering the shapes of the specimen cells. We considered it unlikely that this would influence affinities, but very likely that it would affect rate of dye uptake (cf. Horobin 1988, p 67). So instead of the smeared or spun cells of routine blood and marrow preparations, we investigated cell monolayers derived from suspension-fixed preparations of cultured cells grown for cytogenetic study. Note that we used the standard fixative of cytogenetics, namely methanol-acetic acid, and not the pure methanol of the haematologists. Whilst this allowed us to investigate a practical system of routine significance, it does unavoidably introduce an ambiguity into comparisons of the cytogenetic and haematologic preparations.