Analysis of human spermatozoa by fluorescence in situ hybridization with preservation of the head morphology is possible by avoiding a decondensation treatment

Purpose: Development of a hybridization technique for spermatozoa allowing the preservation of the head morphology. Methods: FISH analysis of fixed semen samples from oligoasthenoteratozoospermia (OAT) patients with a normal somatic karyotype attending the Cytogenetics and the IVF Laboratories of a University hospital for semen analysis. In situ hybridization with centromeric probes for chromosomes X, Y, and 18 and locus specific probe for chromosome 21. Results: More than 95% of the sperm heads showed clear hybridization signals and a conserved morphology including the visualization of the tail. Few cells with splitted signals were not considered. Conclusions: This is the first description of a simple and fast hybridization protocol for spermatozoa without a decondensation step, allowing preservation of the morphology of the sperm head that is particularly useful to correlate abnormal spermatozoa with specific chromosome aneuploidies. With this technique we were able to avoid troubles in interpretation of FISH spots that does not depend on the quality of nuclear decondensation, as it is the case in the previously described methods. Our goal was to demonstrate the efficiency of the method without loosing sperm head morphology. Further studies are needed to correlate the aneuploidy rates for specific chromosomes with sperm morphology.