Abstract
These experiments were carried out to obtain basic information necessary of the success of in vitro culture of blastomeres separated from mouse embryo. Total 446 single blastomeres separated from 2-, 4- and 8-cell mouse embryos by protease treatment (0.5% in Whittingham's medium), were cultured under the gas phase of 5% CO2 in air at 37$^{\circ}C$. whittingham's medium was used for culture of blastomeres. The results obtained in these experiments were summerized as follows: 1. Of total 446 blastomeres cultured, 127(87.0%), 134(73.2%) and 77(65.8%) blastomeres separated repectively from 2-, 4- and 8-cell embryos were developed to morula or blastular stages. 2. The numbers of blastomeres, being separated from 2-. 4- and 8-cell embryos and developing to blastocysts containing inner cell mass, were 97(76.4%), 86(64.2%) and 33(42.9%) respectively. 3. After in vitro culture of the blastomeres, the incidence of trophoblastic vesicles increased with the development of the cell stage of embryo. In case of blastomeres separated from 8-cell embryos, 50.6% of blastomeres that developed to blastular stage was trophoblastic vesicles.