1. a rapid method of preparing insect polytene chromosomes for microscopic investigation without sectioning them. The organ is simply squashed in a drop of stain placed between slide and coverslip. See aceto-orcein. 2. a method of preparing giant polytene chromosomes for localization of specific DNA sequences via in situ hybridization. Larval salivary glands are quickly squashed in an appropriate fixative between slide and coverslip, frozen, and the coverslip removed. The squashed specimens are then dehydrated and prepared for hybridization with labeled nucleic acid probes. See in situ hybridization.
Subjects: Genetics and Genomics.