The reduction of chromosome number in meiosis is determined by properties built into the chromosomes

In meiosis I, two chromatids move to each spindle pole. Then, in meiosis II , the two are distributed, one to each future gamete. This requires that me iosis I chromosomes attach to the spindle differently than meiosis II chrom osomes and that they regulate chromosome cohesion differently. We investiga ted whether the information that dictates the division type of the chromoso me comes from the whole cell, the spindle, or the chromosome itself. Also, we determined when chromosomes can switch from meiosis I behavior to meiosi s II behavior. We used a micromanipulation needle to fuse grasshopper sperm atocytes in meiosis I to spermatocytes in meiosis II, and to move chromosom es from one spindle to the other. Chromosomes placed on spindles of a diffe rent meiotic division always behaved as they would have on their native spi ndle; e.g., a meiosis I chromosome attached to a meiosis II spindle in its normal fashion and sister chromatids moved together to the same spindle pol e. We also showed that meiosis I chromosomes become competent meiosis II ch romosomes in anaphase of meiosis I, but not before. The patterns for attach ment to the spindle and regulation of cohesion are built into the chromosom e itself. These results suggest that regulation of chromosome cohesion map be linked to differences in the arrangement of kinetochores in the two meio tic divisions.