Analysis of TEST (TES and Tris) yolk buffer effects on human sperm

Abstract

Objective: To assess different parameters of TEST (TES and Tris) yolk buffer (TYB) treatment of human sperm that may contribute to the biologic effects of TYB on sperm function.

Design: The influence of TYB treatment on occurrence of acrosome reactions was studied, as was the influence of the concentration of acrosome-reacted sperm reacted by TYB or Biggers-Whitten-Whittingham medium (BWW) incubation on penetration levels in the sperm penetration assay (SPA). The necessity for the TYB to achieve enhanced SPA performance as well as the effect of heat shock on sperm also were studied.

Setting: Andrology laboratory of a university hospital.

Patients: Sperm donors.

Main outcome measures: Sperm penetration levels in the SPA and acrosomal loss as evaluated by a fluorescent lectin staining technique.

Results: Sperm incubated in TYB for 42 to 46 hours at 4 degrees C demonstrated a higher rate of acrosomal loss than did sperm capacitated in BWW media for 20 to 22 hours. The difference was not significant. When insemination concentrations were normalized to identical concentrations of acrosome-reacted sperm, TYB treated specimens demonstrated much higher penetration levels compared with BWW specimens. Samples incubated in BWW versus TYB for 42 to 46 hours at 4 degrees C before heat shock had identical penetration levels. Samples washed with 37 degrees C BWW (positive heat shock) had significantly higher penetration levels than did samples washed with 4 degrees C BWW (negative heat shock).

Conclusion: Although TYB treatment does increase the occurrence of acrosome reactions, this alone does not account for the dramatic increase in penetration levels in SPA seen with these samples. TEST yolk buffer is not required for enhancement of penetration, and the heat shock step of the procedure seems to be most important for enhancement of sperm fusion ability in the SPA.