Recovery of human sperm motility and ability to interact with the human zona pellucida after more than 28 years of storage in liquid nitrogen.

Six donor semen samples were evaluated after 28 years cryopreservation in liquid nitrogen. The results showed that the samples retained good postthaw motility recovery and normal levels of binding to the human zona pellucida and that four of the five samples tested also gave normal levels of zona-induced acrosome reaction. In conclusion, human sperm can survive very long-term storage, which is pertinent information for clinicians referring boys and young men for sperm banking before chemotherapy.