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Molecular mechanisms of regulating mammalian sex and problems of fractionating spermatozoa

: We present results of a study devoted to genetic determination and to the mechanism of primary sex differentiation in mammals. Progress is achieved in the mapping of a Y chromosome region necessary and sufficient for testis determination in man (TDF) and mouse (Tdy). We discuss a possible role in sex regulation of a recently described highly conservative locus from this region, ZFY (and similar loci within other chromosomes probably coding for Zn-binding proteins, transcription regulators) and H-Y antigen as well. We note that neither locus ZFY nor H-Y can play the role of TDF (Tdy) and that studies in this direction should be carried out. Numerous works on fractioning according to sex of spermatozoa of mammals including man are critically reviewed. Contradictory data exist in literature concerning the applicability of different approaches for this purpose: from fractioning based on different inherent mobility of different sex cells or gel-filtration, to the sorting in a flow cytometer equipped with a laser light source and a computer. However, in many cases the principle underlying this or that method of fractionation and determining the positive results, i.e. the statistically important shift of the sex ratio as compared with the initial sperm, remains unclear. It is stated that on the immunological and electrophoretic approaches might appear most promising for practical application, and in cattle-breeding as well. Modern procedures for sex testing and the fertility control of spermatozoa are also examined.