Study of aneuploidy in normal and abnormal germ cells from semen of fertile and infertile men

This study was undertaken with the aim of investigating the cytogenetic constitution of normal as well as abnormal spermatozoa and immature germ cells found in semen of normal men and infertile patients. A specific protocol of double in-situ hybridization for chromosomes 1 and 17 based on colorimetric detection of the hybridization signals (ISH) and brightfield microscopy analysis of cellular morphology was applied. Also the influence of paternal age on sperm aneuploidy was investigated. We found that, at least in the age range analysed (28-54 years) and for semen of good quality (total normal motile counts above 10 x 10(6)) (n = 17), paternal age has no influence on baseline rates of sperm aneuploidy. However, with decreasing semen quality (total normal motile sperm counts below 5 x 10(6)) (n = 6) significantly higher rates of sperm aneuploidy for autosomes 1 and 17 were scored (0.8 versus 1.43%) (P < 0.001). Regardless of the type of semen analysed, a number of morphologically abnormal spermatozoa were found to be hyperhaploid or diploid in a high percentage of cases (20 and 10% respectively). The same was found for immature germ cells (aneuploidy rate of 18%). We conclude that in infertile men with poor quality semen a direct relationship may exist between the impairment of the spermatogenesis process (as reflected by an increased production of morphologically and cytogenetically abnormal germ cells) and rates of baseline aneuploidy occurring in normal spermatozoa. Infertile couples undergoing assisted reproduction treatment need to be counselled about the risk of using spermatozoa which may carry higher rates of non-disjunction for different chromosomes. While sperm hyper- or hypohaploidy for some chromosomes (X,Y) implies counselling couples about the risk of abnormal phenotype in their offspring, most autosomal sperm aneuploidies probably translate only into lower rates of embryo fertilization and survival.