Recombinant human activin A stimulates development of bovine one-cell embryos matured and fertilized in vitro

The effects of recombinant human activin A on the development of bovine one‐cell embryos matured and fertilized in vitro were investigated. In experiment 1, one‐cell embryos were cultured in a chemically‐defined medium, of modified synthetic oviduct fluid supplemented with 1 mg/ml polyvinyl alcohol (mSOF‐PVA), containing different concentrations of activin (0, 0.1, 1, 10, and 100 ng/ml) until 240 hr after in vitro fertilization. The addition of ‐1 ng/m activin to mSOF‐PVA improved development to the blastocyst stage (14.5–17.1%), compared with no addition of activin (5.6%). However, there was no significant difference in hatching rate of embryos among treatments. In experiments 2 and 3, the embryos were also cultured in MSOF‐PVA at various periods of exposure to 10 ng/ml activin to evaluate (development to the morula and blastocyst stages, respectively. The proportion of morulae was significantly higher in culture with activin at 20–120 hr postinsemination (37.2%) than with control (25.7%). Total number of cells in morulae at 120 hr postinsemination significantly increased by the addition of activin at 20–72 hr (26.1 cells) and 20–120 hr (24.2 cells) postinsemination, compared with control (20.1 cells). When activin was added to the medium during 20–120 hr and 20–192 hr postinsemination, the percentages of blastocysts (18.0% and 18.7%, respectively) were significantly higher than in the control (9.6%). However, the total number of cells in blastocysts was not significantly different. These results demonstrate that activin stimulates the development of bovine one‐cell embryos to the morula and blastocyst stages in vitro. © 1996 Wiley‐Liss, Inc.