Staining of granulopoietic agar colonies with a modified Papanicolaou technique.

The aceto-orcein method of staining agar cultured granulopoietic marrow cells has not been entirely satisfactory. In staining whole colonies the original colony structure is lost and the colony cells have blurred cytoplasm. A slight modification of the Papanicolaou technique used for staining vaginal smears improved the quality of stained granulopoietic agar preparations. Smeared Papanicolaou stained colony cells could be compared with smeared ordinary Giemsa stained blood and marrow cells. The Papanicolaou method enabled staining of agar colonies without manipulation of the original colony structure. The preparations of transferred intact colonies had cells with distinct cytoplasm and clear cellular outlines and a background without disturbing masses of stained agar.