Pregnancy by the tubal transfer of embryos developed after injection of round spermatids into oocyte cytoplasm of the cynomolgus monkey (Macaca fascicularis).
BACKGROUND
Round spermatids have been used as substitute gametes in basic reproductive research and in infertility clinics. In humans, however, the efficiency of fertilization and pregnancy is generally much lower after round spermatid injection (ROSI) than after injection with mature sperm. We examined the ability of round spermatids to support embryonic development using a non-human primate as a model. We chose cynomolgus monkeys because, as in humans, their round spermatids have the oocyte-activating capacity of mature sperm.


METHODS
We examined fertilization and subsequent development of embryos after ROSI and then transferred the embryos into the oviducts of female monkeys.


RESULTS
Seventy-seven per cent of survived oocytes were activated and had formed pronuclei or the second polar body; 79% of the oocytes cultured developed to the 2-cell stage, and 23% developed to the blastocyst stage. Ultrasonography showed a normal-sized fetus in the uterus of a recipient, but the fetus spontaneously aborted at day 103.


CONCLUSIONS
The round spermatids of cynomolgus monkeys can be used as substitute gametes to support embryonic development at least to mid-gestation. This non-human primate is a suitable animal model for round spermatid conception in mammals, especially humans, and for biological and genetic characterization of events following ROSI.
Ogonuki
Narumi
N
Tsukuba Primate Center for Medical Science, National Institute of Infectious Diseases, Hachimandai-1, Ibaraki 305-0843, Japan.
Tsuchiya
Hideaki
H
Hirose
Yoshihiro
Y
Okada
Hironori
H
Ogura
Atsuo
A
Sankai
Tadashi
T
D000818:Animals; D004624:Embryo Transfer; D005314:Embryonic and Fetal Development; D005260:Female; D005865:Gestational Age; D008252:Macaca fascicularis; D008297:Male; D023421:Models, Animal; D011247:Pregnancy; D011256:Pregnancy Outcome; D020554:Sperm Injections, Intracytoplasmic / Q000379:methods*; D013087:Spermatids