Counting cross-overs: characterizing meiotic recombination in mammals.

Until recently, most of our understanding of meiotic recombination has come from studies of lower eukaryotes. However, over the past few years several components of the mammalian meiotic recombination pathway have been identified, and new molecular and cytological approaches to the analysis of mammalian meiosis have been developed. In this review, we discuss recent advances in three areas: the application of new techniques to study genome-wide levels of recombination in individual meioses; studies analyzing temporal aspects of the mammalian recombination pathway; and studies linking the genesis of human trisomies to alterations in meiotic exchange patterns.