Analysis of Heteroploidy Produced by Chloracetophenone

Abstract

THE problem of demonstrating and analysing the degree of ploidy of non-dividing cells is continually arising in different contexts, for example, in cancers, or giant cells in tissue culture. Chromosome counts may not be available in such material, and recourse must be had to indirect methods such as those reviewed by Fankhauser and Humphrey¹, including measurement of cell and nuclear volume, nuclear spacing, projected areas of uncountable mitotic figures, counts of heterochromatic spots and maximum number of nucleoli. Huskins demonstrated polyploidy in nonmitotic plant cells by inducing them to divide with 3-indole acetic acid and counting chromosomes. None of these methods except Huskins's² are entirely independent of prior study in the same material of tissues of known degrees of ploidy, and one of the most reliable methods (maximum number of nucleoli) breaks down when applied to limited material or to mixed tissues of varying ploidy. The interesting paper of Biesele, Poyner and Painter³ utilizes and reviews indirect methods in respect of polyploidy and the related condition of polyteny in mouse cancers, but on plentiful material and with the assistance of chromosome counts.