Fig. 1

Sorting of spermatozoa with FACS. Four fractions of spermatozoa of infertile patients and healthy semen donors were separated with the use of FACS. A The YOPRO1-dye was used for separating apoptotic spermatozoa based on their membrane permeability and has previously been shown to correlate well with the degree of fragmentation of sperm DNA [54]. The chromomycin 3-dye (CMA3) specifically binds to guanosine cytosine-rich sequences in the DNA that compete with protamine and high CMA3− uptake correlates with reduced chromatin condensation and high histone content, whereas low CMA3− uptake correlates with high chromatin condensation [55, 56, 58]. B Representative examples of sorting results for the staining with YOPRO1 and CMA3. The Hoechst 33342-dye or Vybrant Dye Cycle Ruby was used to identify and remove debris from the samples