SEX-SELECTION OF HUMAN SPERMATOZOA - EVOLUTION OF CURRENT TECHNIQUES AND APPLICATIONS

Methods claiming to achieve sex selection by sperm sorting have existe d for many years. Numerous applications for safe and effective selecti on procedures exist in current clinical practice, as sex-linked condit ions could be theoretically eliminated by use of appropriate sperm for fertilization or insemination. Use of such techniques could also addr ess the need to effect family balancing for some couples. Modern preco nception sex-selection methods may be classified into two general type s: those that attempt to segregate spermatozoa on the basis of subtle physical or kinetic features, and those that rely on distinctive nucle ar characteristics unique either to X- or Y-chromosome bearing sperm. Laboratories providing sperm sexing using the former method have been available for some years, although the associated efficiency and repro ducibility are controversial. Sex selection of spermatozoa by chromati n differences has been shown to achieve significant enrichment of X- o r Y-chromosome bearing sperm, but clinical experience in humans is lim ited. The fundamental elements of the two approaches introduced here a re reviewed and compared. Selected key historical concepts in sex sele ction by sperm sorting are outlined, followed by a summary of promisin g areas for future research.