Development of Mongolian gerbil embryos in chemically defined media: effects of osmolarity, glucose and phosphate.

Mongolian gerbil 2-cell embryos were cultured in modified M16. When osmolarity of the medium with 5.0 mmol glucose l(-1) was varied by adjusting the amount of NaCl added, 2-cell embryos at 280, 290, 300 and 310 mOsmol developed to the 8- and 16-cell stages. The incorporation and oxidation of 14C-Methionine were compared between fresh recovered and cultured embryos at the 1-cell to 16-cell stages. Development beyond the 8-cell stage of fresh recovered embryos showed an enhanced rate of total protein synthesis, indicating activation of the transcription process of the embryonic genome. However, we found that the lowest incorporation and oxidation of 14C-Methionine was observed in cultured embryos of the 16-cell stage at 115 h after hCG injection. In the medium without phosphate, glucose promoted development of 2-cell embryos to the 8-cell stage, and low concentrations of glucose were necessary for the development of the 2-cell to 8-cell stages. These results suggest that Mongolian gerbil preimplantation embryos can be cultured in vitro in a chemically defined medium with a low concentration of glucose.