Germ cell transplantation: a potential treatment of severe testicular failure.

Although the process of spermatogenesis is relatively efficient and resistant to damage, male infertility can result from exposure to toxic agents such as chemotherapeutic regimes, radiation, or occupational exposures to chemicals. Other types of infertility may result from migratory defects or poor survival of primordial germ cells during development, abnormal repopulation of the tubules by spermatogonia during development, or low cellularity of the testis (hypospermatogenesis). Presently, there are no effective therapies available to treat these patients. Recent studies in animal models have demonstrated that isolated testicular germ cells collected from testes may be transplanted into sterile recipient mice to regenerate spermatogenesis. This technology will have widespread applications in efforts to manipulate the genome and produce transgenic offspring, to improve agricultural species, to enhance sperm production in endangered species, to improve our understanding of the control mechanisms regulating spermatogenesis, and to treat male infertility.