Efficient production of cynomolgus monkeys via transabdominal uterine puncture embryo transfer†.

Embryo transfer is a key application of assisted reproductive technology in non-human primates, underpinning research in reproductive biology, disease modeling, and conservation. The conventional approach-tubal embryo transfer-typically requires a laparoscopy system and abdominal incision to expose the oviducts and reproductive tract for embryo transfer, and is associated with complex procedures, a high cost, and cumulative reproductive tract injury following repeated surgeries. Moreover, implantation and pregnancy rates decline with increasing recipient age and surgical history, highlighting the need for a rapid, simple, and minimally invasive alternative. Here, using cynomolgus monkeys (Macaca fascicularis) as a model, we implemented a transabdominal uterine puncture method. This technique involves the direct introduction of in vitro cultured embryos into the uterine cavity by means of an ultrasound-guided needle. In a cohort of 37 recipients, transabdominal uterine puncture yielded confirmed implantation in 19 animals (51.35%). Importantly, implantation and pregnancy outcomes in older animals and in those with prior reproductive surgeries were substantially higher than rates historically observed with tubal embryo transfer. Gestation assessments and neonatal examinations revealed no discernible abnormalities or increased perinatal complications in offspring produced via transabdominal uterine puncture, compared with controls, supporting the method as an efficient and safe embryo transfer strategy for non-human primates.