WEST LAFAYETTE, Ind. -- In a popular Dr. Seuss book, Horton the elephant is tricked into hatching a bird's egg. Now, in a real-life story, scientists have "tricked" a mouse into producing an elephant egg. That development could boost breeding programs for endangered species and might address some fertility problems in humans.
Purdue University researcher John Critser, working with researchers at the Advanced Fertility Institute at Methodist Hospital of Indianapolis, has transplanted ovarian tissue, collected from an African elephant and frozen for preservation, into a mouse, inducing the mouse to successfully produce an elephant oocyte, or egg.
The results, published in the October issue of the journal Animal Reproduction Science, indicate that transplanted ovarian tissue may be used to regenerate reproductive cells for a wide variety of female mammals, including less-studied, rare or endangered species.
The current research was performed as a follow-up to two studies published last year by Critser and others that showed cryopreserved ovarian tissue from different species could produce viable eggs in immune- compromised mice, a strain of mice that can readily accept foreign tissues because its immune system has been suppressed.
In those experiments, cryopreserved ovarian tissues from outbred mice or sheep were transplanted into immune-compromised mice. After hormone production was established, those mice with "mouse-to-mouse" transplants were mated and produced live offspring.
Critser says the elephant egg, in theory, could be fertilized in vitro and then transplanted into a female elephant. However, procedures to isolate and fertilize eggs from elephants and other exotic animals, and the techniques of transferring embryos into live animals, will require additional investigation and development, he says.