Potential use of animal male germplasm for the preservation of endangered species

Abstract

Animal germoplasm comprises cells or tissues that can be used to generate new individuals. It can be used for endangered species reproduction. Besides gametes, animal germoplasm also includes diploid cells such as stem cells, potentially able to divide indefinitely. Spermatogonial stem cells (SSCs) give rise to sperm in the testis (spermatogenesis). SSCs offer many biotechnological possibilities. Contrary to the female oogonial stem cells, numerous SSCs can be obtained during the postnatal prepubertal pre-meiotic period. SSCs can be isolated, amplified in vitro and cryopreserved to establish cell-lines. SSCs can also be induced to differentiate in vivo and in vitro. In vivo methods are based on the transplantation of SSCs from a donor testis to a recipient with endogenous spermatogenesis depleted. These techniques have been established mainly in laboratory rodents and have promising potential for domestic and wild animals. The last could be used as donors of SSCs and recipients could be common philogenetically-related, non-threatened domestic species. Thus, domestic males would eventually produce endangered species sperm. Testicular cells or tissues can also be transplanted to the back-skin of mouse where spermatogenesis resumes and foreign sperm generates, as tested in many species. Spermatogenesis in vitro has been accomplished only in mice. Regardless of the method used, sperm coming from SSCs could be used through artificial reproductive techniques to generate embryos and new individuals to repopulate unstable ecosystems or to genetically improve animal production systems.