A rapid procedure for the staining of chromosomes in fixed animal materials

This paper presents a very simple and reliable procedure for the staining of animal chromosomes employing dyes, such as pyronin G, acridine red, rhodamine B, rhodamine 3GO, belonging to aminoxanthene group and brilliant cresyl blue and methylene violet 3RD, belonging to quinone-imine group. The procedure has been tried on sections of the grasshopper and mouse testes fixed in Dutt's modification of Nawaschin mixture. The method is to deparaffinise sections and then to stain with aqueous solution of these dyes for 2--3 minutes, rinsed with water and dehydrated through grades of ethanol, keeping for 15--30 seconds in each grade with several dips. Preparations are then cleared in xylene and mounted. Stained preparations following this procedure revealed excellent colouration of the chromosomes at all the various stages of mitosis and meiosis, particularly in the case of the grasshopper. Mouse chromosomes stained with these dyes following the same method revealed perfect colouration of the fully condensed chromosomes at all stages of mitosis and meiosis but not of the very early stages, except the sex chromosome. Moreover, grasshopper testis sections when treated with cold concentrated phosphoric acid for varying time-periods and then stained with these dyes also revealed excellent colouration of the chromosomes. The implications of these findings have been discussed.