A Technique for the Morphological Examination of Hemopoietic Cells Grown in Agar

Histological preparations of hemopoietic cells growing in colonies in soft agar were made using a modified squash technique. Colonies were fixed in the Petri dish with 3:1 acetic-alcohol mixture for 1 hour. Individual colonies were pricked out with a microhematocrit tube and placed on a slide. Squash preparations of the cells were then made by the standard method. Preparation for staining the cells was made by immersing the slides in methyl alcohol for 10 minutes. The slides were finally treated with phosphate buffer at pH 6.4 for 45 minutes before staining with MacNeal’s tetrachrome. This technique allowed the recovery and cytological examination of most of the cells growing in a single colony.