Ultrasound-guided non-surgical embryo collection in the common marmoset

Experimental primate embryology has been hampered by limited access to embryos. In addition to surgical techniques, the less stressful non-surgical technique of uterine flushing has been developed but has had only limitedly used in recovering pre-implantation embryos from marmoset monkeys. In this study, we introduce the use of ultrasonography during marmoset non-surgical uterine flushing to make the cannulation easier, to further reduce stress, and to ensure thorough uterine flushing. We were able to cannulate in 99% of the transcervical cannulation attempts, repeat the flushing up to 17 times with the same animal, and recover up to 90% of the ovulation products. We also found that 8-cell or earlier stage embryos could be frequently obtained by non-surgical uterine flushing at 4 or 5 days after ovulation. The easiness and effectiveness of this novel ultrasound-guided technique will enable more research groups to study marmoset embryology and facilitate progress in this field.