Cryopreservation of human spermatozoa within human or mouse empty zona pellucidae

Objective: To compare the empty zona pellucidae (ZP) of different species f or use in the cryopreservation of spermatozoa. Design: Prospective study. Setting: An IVF unit of a medical center. Patient(s): Patients with azoospermia, oligoasthenozoospermia, or normal sp ermatozoa. Intervention(s): Human and mouse ZP were prepared by evacuating the cytopla sm of oocytes or embryos. The evacuated ZP were injected with spermatozoa f rom patients with severe oligoasthenozoospermia and from healthy, fertile m en. After the freezing and thawing procedure, the spermatozoa were aspirate d outside the ZP. Main Outcome Measure(s): The number of spermatozoa per ZP, the number of mo tile sperm before freezing and after thawing, the number of sperm lost per ZP after freezing, and the sperm recovery rate were compared according to t he different origins of the ZP and the sperm. Result(s): The number of spermatozoa, number of motile sperm before freezin g and after thawing, number of sperm lost per ZP, and sperm recovery rate w ere comparable in all groups. The total mean number of motile sperm before freezing and after thawing, the mean number of nonmotile sperm after thawin g, the mean number of sperm lost after thawing, and the sperm recovery rate were 14.5%, 11.8%, 1.0%, 1.5%, and 82%, respectively. Conclusion(s): Zona pellucidae are an ideal vehicle for the cryopreservatio n of sperm collected by testicular sperm extraction or microsurgical epidid ymal sperm aspiration or from patients with severe oligoasthenozoospermia. There were no differences when human and mouse ZP were used for sperm stora ge.