Differences in the DNA-stainability of spermatozoa from fertile and suspected infertile men

The aim of this work was to determine whether it is possible to distinguish between fertile (control group, already fathers) and infertile men (suspec ted infertility), by comparing the fluorescence intensity of the sperm-DNA after incubation with appropriate dyes. First we examined two different DNA -specific dyes (DAPI and YOYO-1) using bull spermatozoa. Based on good resu lts in immunohistochemical applications, YOYO-1 was chosen for further work . The fluorescence-intensity of 200 single, morphologically normal spermato zoa in each semen sample were measured in a cytophotometer, means + SD dete rmined and histograms delineated. Of 20 samples from the control group, 17 had markedly higher fluorescence-intensity than did 7/15 of the suspected i nfertile men. It is concluded that the DNA of the latter seven samples was less accessible to the dye than was the DNA of the control group. There are cases of infertility known in which there is loss of one or more of the DN A-binding proteins, which in spermatozoa are mainly (85%) protamines. The r elationship between the stainability of the sperm-DNA and the packaging wit h DNA-binding proteins is discussed. Two of the histograms showed abnormali ties in the distribution of the fluorescence-intensities, one sample was ex tremely fragile and most of the sperm lysed during the staining-procedure. Five samples showed normal histograms in comparison with the control group.