Figure 1: SLC-4.5. The tube on the left shows the SLC-4.5 prior to centrifugation, with 4.5 mL extended boar semen on top of 4.0 mL Androcoll-P. The tube on the right shows the preparation after centrifugation with the sperm pellet clearly visible in the bottom of the tube. Note the white line marking the interface between semen and colloid after centrifugation. This consists of spermatozoa that have not been able to pass into the colloid because of poor motility, abnormal morphology, or damaged chromatin.