Editorial Comment:Heat is well established to be toxic to sperm. Surprisingly little is known about which environmental heat sources disturb human spermatogenesis in vivo and by how much. Most studies focus almost completely on how much the scrotal temperature increases when exposed to a heating source. To their credit, these investigators studied bulk seminal parameters, sperm nucleic acid characteristics and sperm mitochondrial function at various points after sauna exposure and observed a reversible degradation of all. While the study lacked a true parallel control group, it is closer to an evidence-based recommendation regarding sauna use than many similar published investigations of various heating sources, namely that men who are trying to impregnate their partners should stay away from the sauna.

The majority of 47, XYY males are fertile and contribute to produce chromosomally normal children. In 47, XYY carriers, most meiotic studies indicated that the extra Y chromosomes were lost in the pre-meiotic stages, but in some cases the presence of one X and the two Y chromosomes has been detected during prophase I as an X univalent plus a YY bivalent. The aim of this study was to describe sperm parameters and meiotic segregation in a case of an infertile man with a 47, XYY karyotype. Sperm morphology was evaluated for the first time by transmission electron microscopy highlighting apoptosis and necrosis as the most frequent pathologies. Meiotic segregation was explored by fluorescence in situ hybridisation technique, which makes us capable of detecting aneuploidies of sex chromosomes. The fact that the frequency of 1818XY diploidy was very high reveals an error occurring during first meiotic division. Polymerase. chain reaction analysis did not show any Y microdeletion. The combination of these two techniques led us to clarify the status of the spermatogenic process, showing an altered meiotic segregation concomitant with the presence of sperm apoptosis and necrosis in a patient 47, XYY.

The sperm 'round head' defect, also known as globozoospermia, is an uncommon alteration of sperm morphology generally characterised by 100% round headed sperm totally lacking an acrosome. This alteration is a genetic sperm defect as demonstrated by analysing the incidence of these alterations in a population of infertile men showing a history of consanguinity and cases belonging to the same family. Ultrastructural characteristics and meiotic segregation in spermatozoa from two patients affected by 'round head' sperm defect were investigated. The sperm quality was examined by light and transmission electron microscopy (TEM) and fluorescence in situ hybridization (FISH) analysis was performed in order to investigate the meiotic behavior of chromosomes namely gonosomes and chromosome 18. TEM analysis, mathematically elaborated, clearly diagnosed the 'round head' genetic sperm defect and highlighted at the same time the presence of other phenotypic alterations belonging to pathologies such as immaturity, apoptosis and necrosis. It is possible to hypothesize that round headed sperm could be a 'weak phenotype' allowing the sperm pathologies to overlap with a sperm defect of genetic origin, further compromising fertilizing potential. FISH analysis revealed a positive correlation between globozoospermia and higher disomies of sex chromosomes and diploidies suggesting a higher risk of creating an aneuploid embryo after intracytoplasmic sperm injection.