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Cincinnati Zoo Produces Cats Using "Glass" Sperm

The Cincinnati Zoo has produced what's believed to be the first non-human offspring using "glass" sperm. They are kittens named Elsa and Vito.

The Center for Conservation & Research of Endangered Wildlife (CREW) harvested domestic cat sperm and preserved it in ultra-rapid freezing liquid nitrogen to form "glass" rather than ice crystals. This process is called vitrification.

How it works:

  • Cat semen is diluted with soy lecithin and sucrose (cryoprotectants)
  • The mixture sits for 5 minutes
  • It is pipetted in small volumes directly into liquid nitrogen
  • Tiny glass marbles of frozen sperm form

Three females were inseminated with vitrified sperm.  According to the Zoo, all three conceived, with two progressing to term.
Domestic cats now endangered cats later

Bill Swanson, CREW's Director of Animal Research, says, "Cryopreservation of cat semen for assisted reproduction can be challenging, requiring technical expertise and specialized equipment." But he says, "The use of vitrification simplifies the process and makes it possible for almost anyone with minimal training and supplies to freeze semen."

Research suggests this process may produce fishing cat or ocelot offspring. The Zoo hopes to eventually expand semen banking of endangered cats to aid in conservation throughout the world.


The lead author of this study, veterinary student JaCiara Johnson, will present her results at the American Association of Zoo Veterinarians' Annual Conference.

The only other reported birth from laparoscopic oviductal AI using vitrified sperm was a baby born at a fertility clinic in Chile in 2011.

Ann Thompson has decades of journalism experience in the Greater Cincinnati market and brings a wealth of knowledge and expertise to her reporting.