An Air-Drying Technique for Flattening Chromosomes in Mammalian Cells Grown<i>In Vitro</i>

TLDR

The method was developed to facilitate analysis of chromosome complements in freshly isolated monkey kidney cortex cells grown on glass and in altered monkey cells grown on glass or in suspension. Cells were treated with hypotonic solution or colchicine, then fixed in acetic alcohol, air‑dried, and could be stored or stained immediately, with preparations made permanent by a dry‑ice schedule without loss or distortion. The technique yields uniform, complete flattening of cells without chromosome fragmentation, outperforming manual pressure.

Abstract

AbstractThe method described was developed to facilitate the analysis of chromosome complements in cells freshly isolated from monkey kidney cortex and grown on glass, and in “altered” monkey cells grown on glass or in suspension. Cells were treated with hypotonic solution (quarter-strength Tyrode or diluted medium) for 30 min, or with colchicine in a final concentration of 25 μg/ml (.0025%) for 12-18 hr followed by hypotonic salt solution for 5 min, then fixed in acetic alcohol (1:3) for 5 min. With cells centrifuged from suspended cultures, addition of fixative had to be gradual. Directly after fixation, films of cells on slides were air dried completely. This produces a more uniform and complete flattening of cells than can be achieved by manual pressure; yet, fragmentation of chromosome complements does not occur. Fixed and air dried slides may be stored for days without deterioration or they may be stained immediately in 2% natural orcein (G. T. Gurr, London) in 50% acetic acid. Preparations can be made permanent by a dry ice schedule, without loss, shrinkage, or distortion of cells.