Fertilization by Intracytoplasmic Sperm Injection and Subsequent Embryo Development In Vitro to Blastocysts in Japanese Monkey (Macaca fuscata)

Abstract

Intracytoplasmic Sperm Injection (ICSI) has been widely applied for curing human infertility. In this study the developmental potential of Japanese monkey embryos produced by ICSI is reported in a practically relevant system. Oocytes retrieved by laparoscopy from follicles in ovaries of gonadotrophin-stimulated fertile females were fertilized by ICSI using spermatozoa obtained from a fertile male. An additional chemical stimulus was not necessary to achieve oocyte activation with pronuclear formation after ICSI. Successful fertilization was confirmed by extrusion of the second polar body and the presence of both male and female pronuclei at 18-20 h post-ICSI. Some two-cell stage embryos obtained by ICSI were transferred to synchronous recipients and the others were cultured in CMRL medium for 168 h to assess their developmental competence. Oocytes collected laparoscopically from hyper-stimulated monkey ovaries were fertilized by ICSI and completed preimplantation development in vitro, however no pregnancy was confirmed after embryo transfer. This study demonstrates for the first time that the oocytes of the Japanese monkey are able to support advanced embryonic preimplantation development in vitro. It is suggested that the Japanese monkey is an excellent preclinical model for examining and understanding many aspects of ICSI for endangered primates.