Bovine embryo development produced by in vitro fertilization cultured withoviductal cell or conditioned medium and transfer to recipients

The in vitro development of matured and fertilised bovine oocytes was compa red between two culture systems. Oocytes were collected by aspiration of fo llicles of 3-8 mm in diameter using an 18g needle. After morphological sele ction the oocytes were incubated at 39 degrees C, 5% C0(2) and 95% relative humidity, for 22 hours. Afterwards, oocytes were incubated with spermatozo a selected by the Percoll gradient system. The rate of nuclear maturation a nd fertilisation was 93.7% (74/79) and 76.9% (50/65), respectively. A total of 252 zygotes were cultured; 102 with oviductal cells and 150 in conditio ned medium. The in vitro development on day 2 of culture (4- or 8-cell embr yos) was 62.7% (64/102) for the zygotes co-cultured with oviductal cells an d 66.7% (100/150) for the zygotes cultured in conditioned medium. The devel opment to the morula stage was 17.6% (18/102) for the zygotes co-cultured w ith oviductal cells and 13.3% (20/150) for the zygotes cultured in conditio ned medium. A statiscally significant difference was not found in the devel opment of 4-8-cell embryos or morula. The development of embryos up to the blastocyst stage was 15.7% (16/102) for the zygotes co-cultured with oviduc tal cells. Two blastocysts were transferred to the uterine horn ipsilateral to the CL in two recipients by non-surgical embryo transfer. Pregnancy was confirmed by ultrasonography at 42 and 57 days, detecting the presence of one conception in each animal, This work has shown that in vitro inseminati on of bovine oocytes with espermatozoa prepared with modified BO and co-cul tured with oviductal cells, can develop to the blastocysts stage, unlike th e ones cultured with conditioned medium. Finally, it is important to mentio n that this is the first communication in Chile of pregnancy after in vitro fertilization of bovine oocytes.