Sublethal sperm freezing damage: Manifestations and solutions

Semen cryopreservation is an important tool for artificial breeding, species conservation and human reproductive medicine. However, sublethal freezing damage remains an important limitation of the cryopreservation process, inevitably leading to reduced fertility in vivo. This review explores several facets of sublethal freezing damage, touching on cryocapacitation, the generation of reactive oxygen species and alterations to sperm proteins, lipids and sugars. The effects of sublethal freezing damage on sperm performance in vivo are also discussed, examining fertile lifespan and interaction with female reproductive tract immune cells, mucus and oviductal cells. Finally, the cryoprotective potential of whole seminal plasma and individual proteins are explored.