The present invention relates to a method for obtaining a spermatozoid cell population with improved fitness which comprises contacting the starting spermatozoid population with a binding agent recognizing the CD10 biomarker and isolating spermatozoids from the starting population which do not bind to said biomarker. The invention also relates to the spermatozoid cell population, which can be used to fertilize an ovum, and to the embryo obtained. The invention also relates to a method for determining the fitness of sperm for fertilization based on the percentage of the spermatozoid population not carrying the CD10 biomarker.
