The rat studies also may help the researchers develop optimal culture conditions for in vitro maturation and fertilization, and they may improve techniques for transferring embryos into live animals. These procedures then might be applied to rare or endangered species, Critser says. He and his group also are looking at ways in which cryopreserved ovarian tissue from humans can be used to circumvent fertility problems caused by certain illnesses or medical conditions. Critser and a group at Methodist Hospital have collected samples from a human patient and are applying for funding to expand their study. Critser is a reproductive physiologist who serves as adjunct associate professor in Purdue's School of Veterinary Medicine.
Cryobiology routinely is used to preserve tissues such as blood and skin.
Human sperm banks also use this method to distribute more than 100,000 units of preserved semen every year. Since 1989, Critser has studied ways to apply cryobiology to preserve genetic materials of endangered species. Biodiversity on the planet is rapidly declining. There is a growing interest in finding ways to preserve the genetic material from rare and endangered species, with the intent to both study the genetic information and to reintroduce it into the population through planned breeding programs. In most cases, scientists have been working with sperm because it's easier to collect and store.