THE BEHAVIOR OF MEIOTIC CHROMOSOMES IN MA LE-MICE PACHYTENE OF DIFFERENT TRANSLOCATIONS (RB(8, 17), T(16, 17) 43H)

The electron microscopic analysis of synaptonemal complexes of the Rob ertsonian translocation heterozygotes (Rb/T) and heterozygotes of the reciprocal translocation (Rb(8, 17)/T(16, 17) 43H revealed three types of translocation configurations (TC). The observed TC were subdivided into three types according to the manner of synapsis: 1) full synapsi s of homologues forming trivalent with intersticial centromer in 15%; 2) the centromeric asynapsis (8 and 17-16 chromosomes forming trivalen t with the extension region of asynapsis and breakpoint of the recipro cal translocation on chromosome 17 in 70%; 3) centromeric asynapsis (o nly single chromosome 17-16 of trivalent, when the break point of reci procal translocation and the absence of centrometric asynapsis of anot her chromosome 8 formed trivalent in 15%). The frequency of associatio n between trivalents and the XY bivalents is 20% and close proximity i s 15% for heterozygotes Rb/T. Which are fertile, while in the sterile heterozygotes Rb(8, 17) / T(16, 17) 43H it is 45% for association and 15% close proximity (total 60%). These data show the significant diffe rences in the contact of translocation configurations with the XY biva lents of fertile heterozygotes, in comparison with the sterile. Thus, it is shown that the chromosome pairing of fertile and sterile mice is clearly distinguished.