Igor I. Katkov

TL;DR: It is suggested that optimal regimes for the cryoprotectant-free cryopreservation of spermatozoa need not be restricted to very fast cooling before storage in liquid nitrogen, a wide range of cooling rates being acceptable.

TL;DR: The history of this problem is covered, and an explanation, through physico-chemical concepts, for one of the most recent developments in this area: the recovery of motile and potent spermatozoa after cryoprotectant-free vitrification is offered.

TL;DR: The vitrification of human spermatozoa in the absence of conventional cryoprotectants is indeed feasible, and the DNA integrity of vitrified sperm is comparable with that shown by standard slow-frozen/thawed spermutozoa, yet the method is quick and simple and does not require special cryobiological equipment.

TL;DR: Vitrification of human spermatozoa with non-permeable cryoprotectants such as HSA and sucrose can effectively cryopreserve the cells without significant loss of important physiological parameters.

TL;DR: Evaluation of two parameters, motility and viability rate of spermatozoa, suggests that all four methods of cooling and warming are suitable for use in assisted reproductive technology, but only the use of open-pulled straws as well as standard open straws allows the isolation of spermutozoa from liquid nitrogen with low potential risk of microbial contamination during freezing and storage.