Overcoming the mouse 2-cell block by co-culture with established cell lines

To overcome the mouse 2-cell block, embryos resulting from in vitro fertilization (IVF) were co-cultured with established cell lines, namely, CHO-K1 (derived from Chinese hamster ovary), CHUIU (derived from Chinese hamster lung), and HEPM (derived from human embryonic palatal mesenchyme). Differences of embryonal development were observed in the different established cell line co-cultures. CHO-K1 were the best feeder cells for overcoming the block, while the CHL/IU exhibited this ability to a much lesser degree. HEPM was not able to overcome the block. Observations of the structure of these established cell lines, revealed variations in the morphology and density of the feeder cells. A large number of villi were observed on the surfaces of CHO-K1 and CHL/IU cells, and the cell density of CHO-K1 was much higher than that of CHL/IU. On the other hand, the surfaces of HEPM cells exhibited no villi or other structures. These findings suggest that the morphology and density of the feeder cells play a role in overcoming the 2-cell block.