Use of Assisted Reproductive Technologies in the Propagation of Rhesus Macaque Offspring1

Abstract

The assisted reproductive technologies (ARTs) as tailored to the production of rhesus monkeys at the Oregon National Primate Research Center (ONPRC) are described. Efficient fertilization of mature oocytes recovered by aspiration from females subjected to follicular stimulation was achieved with fresh or frozen sperm by intracytoplasmic sperm injection (ICSI). Embryo development to the early cleavage stage occurred at high frequency. Cryopreserved embryos showed high postthaw survival and were also transferred in efforts to establish pregnancies. Three methods of transfer were evaluated, two involving embryo placement into the oviduct, laparoscopy and minilaparotomy, and a nonsurgical, transcervical approach that resulted in uterine deposition. Early cleaving embryos (Days 1-4) were transferred into the oviducts of synchronized recipients with optimal results and pregnancy rates of up to 36%. Pregnancy rates were similar when two fresh or frozen embryos were transferred (28- 30%), although more than two embryos had to be thawed to compensate for embryo loss during freeze-thawing. Normal gestational lengths, birth weights, and growth curves were seen with ART-produced infants compared with infants produced by natural mating in the timed mated breeding (TMB) colony at the ONPRC. In 72 singleton pregnancies established following the transfer of ART-produced embryos, the live-birth rate, at 87.5%, was statistically identical to that for the TMB colony. Further development of the ARTs should result in increasing use of these techniques to augment conventional approaches to propagating monkeys, especially those of defined genotypes.

Transgenic rhesus monkeys produced by gene transfer into early-cleavage–stage embryos using a simian immunodeficiency virus-based vector

“…Fifteen embryos were transferred into five pregnant monkeys, who gave birth to four healthy offspring. These rates are significantly higher than those published by most laboratories so far (7,21,22).…”

Generation of macaques with sperm derived from juvenile monkey testicular xenografts

“…The fertilization rate was ~61.8% (34/55) and the zygotes were transferred into 8 female surrogate monkeys. Three recipient monkeys were pregnant with a pregnancy rate of 37.5%, close to that achieved with the ICSI method using sperm from sexually mature monkey males [7,8]. Among the 3 pregnant monkeys, one miscarried 4 months after the embryo transfer and the other 2 monkeys delivered two live monkey infants XG2 and XG3 ( Figure 1N).…”

Efficient reproduction of cynomolgus monkey using pronuclear embryo transfer technique

“…Our observations suggest that the surge of E2 combined with the presence of corpus luteum is a good index for timing the transfer of pronuclear embryos. Transfer of pronuclear embryos at 24-36 h after E2 peak in the presence of new corpus luteum in the ovary resulted in a live birth rate of 64% in this study, significantly higher than in previous reports on cynomolgus monkey (12) and rhesus monkey (24).…”

“…Thus, we performed a set of experiments to investigate whether the pronuclear embryo transfer method can be used for efficient reproduction in primates. As such, we adapted the pronuclear embryo transfer method to the monkey experiments and transferred pronuclear embryos rather than 4-cell or 8-cell embryos into the recipients (23)(24)(25). The present study demonstrates the high efficiency of using a pronuclear embryo transfer technique for the production of IVF-derived baby monkeys.…”