ABSTRACT
The male germ cells, the spermatozoa, are produced in a unique process named spermatogenesis. During this process, spermatogenic stem cells undergo reduction of the genome from diploid cells to haploid cells, as well as unequaled morphological and functional changes. In this respect, spermatozoa are not only the smallest (length of sperm head: 4-5 µm) and most polarized cells (sperm head in front, flagellum at rear) in the body, but also the only cells that fulfill their function outside the body, even in a different individual, the female reproductive tract. Therefore, spermatozoa are highly specialized cells, simply a ‘means of transportation’, that transfer the genetic information from the male to the female, the oocyte for which specific physiological functions of these cells are required. For the sperm cells to acquire these functions, morphological and physiological development of the spermatozoa has to take place. In addition, proper chromosomal and genetic constitution is mandatory, i.e. chromosomal and DNA integrity must be given.
