A simple staining method for the analysis of meiotic metaphase II divisions in the male mouse.

Abstract

During an investigation into the effects of X rays on meiosis in the male mouse (Szemere and Chandley 1975) a staining technique was required that would enable us to make an accurate analysis of dyads2 at metaphase II. Not only were we interested in analysing chromosomal aberrations at this stage, but we also wished to identify with confidence the X and Y chromosomes, and to establish accurate counts of dyad numbers. Conventional staining with carbol fuchsin (Can and Walker 1961) provided adequate means for recognizing sex chromosomes, but centromere positions could not be identified and little morphological detail of autosomal dyads could be discerned. Staining by the BSG barium hydroxide/saline/Giemsa technique (Sumner 1972) as modified for use on meiotic cells of the mouse (Chandley and Fletcher 1973) gave excellent staining of centric heterochromatin, but dyad arms were often pale and indistinct. Other centromere staining methods for murine meiotic cells (Hsu, Cooper, Mace and Brinkley 1971, Polani 1972), gave unsatisfactory results in our hands. By combining carbol fuchsin staining with the BSG centromere staining technique, we have been able to produce a simple and quick technique which gives excellent staining of centromeres, easy identification of X and Y chromosomes and good staining of dyad arms at metaphase II. The technique has also been applied successfully to other meiotic stages of the mouse and to human somatic metaphase chromosomes.