Differential effect of common laboratory treatments on hypoosmotic swelling responses of human spermatozoa

Purpose: The impact of some of the common laboratory interventions on the hypoosmotic swelling (HOS) responses of human-spermatozoa was investigated. Methods: The semen samples underwent different laboratory treatments prior to the standard HOS test, which involved incubation of sperm in the hypoosmotic solution. Fresh semen served as a control for all treatment groups and underwent the same HOS procedure. The HOS-reactive spermatozoa and the type of HOS reactions (swelling types) in each group were identified under a phase-contrast microscope for comparison. Results: All the seven types of HOS responses documented in fresh semen sperm also occurred in the laboratory-processed sperm. The total HOS responses of sperm that underwent cryopreservation, heat shock, and Percoll wash were significantly different from those of the corresponding control. Percoll washing of semen influenced HOS subtypes a and g; cryopreservation affected subtypes a, b, c, and d; and heat shock altered subtypes a,f, and g. In contrast, prolonged postejaculation and cold shock did not affect any of the HOS responses. None of the treatments influenced the d and e responses. Conclusions: These results indicate that the total HOS response value and specific response subtypes are significantly affected by some of the laboratory treatments but not others.