Sperm cryopreservation with empty human or mouse zona pellucidae - A comparison

OBJECTIVE: To compare empty zona pellucidae (ZP) and human of mouse oocytes for sperm cryopreservation. STUDY DESIGN: ZP was prepared by evacuating the cytoplasm of human or mouse oocytes. The evacuated ZP were injected with spermatozoa from patients wit h severe oligoasthenozoospermia from normally fertile men. After a freezing -thawing procedure, the spermatozoa were aspirated outside the ZP. Accordin g to the different origins of ZP and sperm, the spermatozoa number per ZP, motile sperm number before freezing and after thawing lost sperm number per ZP after freezing and sperm recovery rate were compared. RESULTS: Spermatozoa number, motile sperm number before freezing and after thawing, lost sperm number per ZP and sperm recovery rate in all groups wer e comparable. The total mean motile sperm number before freezing and after thawing, mean lost sperm number after thawing and sperm recovery rate were 15.1%, 12%, 1.6% and 80%, respectively. CONCLUSION: ZP is an ideal vehicle for cryopreservation of sperm collected from patients with severe oligoasthenozoospermia. There were no differences between human and mouse ZP for sperm storage.