Spectral karyotyping (SKY) of mouse meiotic chromosomes

The spectral karyotyping procedure of in situ hybridization with chromosome -specific probes assigns a unique colour code to each of the 21 mouse mitot ic chromosomes. We have adapted this procedure to meiotic prophase chromoso mes, and the results show that each of the pachytene or metaphase I bivalen ts can be identified. This technique has the potential to recognize synapti c anomalies and chromosome-specific structural and behavioural characterist ics. We confirm these potentials by the recognition of the heterologous syn apsis of the X and Y chromosomes and by the variances of synaptonemal compl ex lengths for each of the colour-coded bivalents in eight prophase nuclei.