[Detection of numerical chromosomal aberrations in epididymal sperm of mice using three-color FISH with chromosome-specific DNA probes].

To detect malsegregation of chromosomes during meiosis in male mice, three-color FISH using DNA probes specific for mouse chromosomes X, Y and 8 was performed on epididymal sperm decondensed for 30 min each in 10 mmol/L DTT and 4 mmol/L LIS, and conventional chromosome counting was also carried out on C-banded MMII cells. Comparisons between these two methods indicate as the following: (1) three-color FISH is a simple, rapid and sensitive approach; (2) The estimate of the frequency of aneuploidy obtained from three-color FISH analysis is more reliable since extremely large numbers of sperm (more than 10,000 sperm per animal) are scored; (3) The rates of cells arrested at meiosis I and meiosis II (representing diploid sperm) can be detected only by using the three-color FISH approach; (4) Malsegregation of chromosomes occurred during both meiosis I and meiosis II can be detected simultaneously by using this new approach. The probes and scoring criteria used in FISH on interphase sperm nuclei, and the necessity of using three or more chromosome-specific DNA probes to thoroughly evaluate aneugenic effects of factors tested on meiosis in male mice were discussed.