Human embryonic behavior in a sequential human oviduct-endometrial coculture system

Embryonic behavior to blastocyst, hatching, and hatched stages were evaluated in 77, four-cell human embryos that were first grown in oviductal cell coculture and then equally allotted at the eight-cell stage to two coculture systems in a serum-free medium (34 continued on oviductal monolayers, 32 on endometrium monolayers). Sixty-three percent and 40% of embryos expanded and hatched in the sequential oviductal-endometrial coculture system when compared with 41% and 9% in the oviductal system alone, respectively. The sequential coculture system appears to be an improved system over the single human oviductal coculture system.