[The possibilities of separating spermatozoa].

Some methods for the separation of spermatozoa are described, with the aim of: 1. Increasing the "quality" of seminal parameters in subfertile men 2. Separating spermatozoa containing X and Y chromosomes 3. Deleting spermatozoa containing certain genetic information. Mainly gravimetric methods were used and concentration of motile spermatozoa was obtained, but the sperm density was always diminished. None of the methods used so far has been able to increase the fertility index or change the sex proportion of children born after artificial insemination.