Size differences between human X and Y spermatozoa and prefertilization diagnosis

Normal human spermatozoa carry either the X or the Y chromosome. Thedifferences between X and Y spermatozoa (X and Y haploid cells) may existin two areas: the different chromosomes (i.e. different kinds and numbersof genes) and the different sperm structures and functions (i.e. differentgenetic expression). The aim of this study was to determine whether thereare any size between X and Y spermatozoa and whether sperm size and shapevaries between men. Identification of the Y (and X inferred) status ofindividual spermatozoa was carried out by polymerase chain reaction (PCR),amplifying the putative testis- determining gene (SRY) together with acontrol gene (ZP3). PCR amplification of 871 out of 895 (97.3%) singlemotile spermatozoa showed that 444 (51.0%) were Y and 427 (49.0%) wereX-bearing spermatozoa. Of 233 normally-shaped but immobilized spermatozoa,217 (93.1%) were photographed and measured. Statistically, the length,perimeter and area of the sperm heads, and the length of the sperm necksand tails of X-bearing spermatozoa were significantly larger and longerthan those of Y-bearing spermatozoa. Some peculiarities (or variations) inthe X and Y sperm shape and size in individual donors were found. Thepre-screening by micro-measurement of these specific haploidcharacteristics of individual spermatozoa in different donors, which may beclosely related to their different genetic conditions (or diseases), may beimportant in human medicine and animal husbandry, especially in spermprefertilization diagnosis.