Birth of a marmoset following injection of elongated spermatid from a prepubertal male.

The common marmoset is a small nonhuman primate in which the application of transgenesis and genetic knockout techniques allows the generation of gene-modified models of human diseases. However, its longer generation time than that of rodents is a major obstacle to the widespread use of gene-modified marmosets for biomedical research. In this study, we examined the feasibility of shortening the generation time by using prepubertal marmoset males as gamete donors. We collected late round stage spermatids (Steps 5-7), elongated spermatids, and testicular spermatozoa from the testis of a prepubertal 11-month-old male marmoset and injected them into in vitro-matured oocytes. After 7 days in culture, two embryos from elongated spermatid injection and two embryos from sperm injection were transferred into two separate recipient females. The recipient female that received elongated spermatid injection-derived embryos became pregnant and gave birth to one female infant. This is the first demonstration that a spermatid from a prepubertal male primate can support full-term development. Using this method, we can expect to obtain offspring of gene-modified males 6 months to a year earlier than with natural mating.