@article{oai:rakuno.repo.nii.ac.jp:00000369,
 author = {Kobayashi, Masayuki and Terawaki, Yoshinori and Saito, Koichi and Kasuga, Kano and Kojima, Ikuo},
 issue = {2},
 journal = {Zygote},
 month = {May},
 note = {Article, The phenomenon of developmental arrest at the 2-cell stage of zygotes obtained from certain mouse strains during in vitro  culture is known as the 2-cell block. The effect of conditioned medium (CM) with rat hepatoma BRL cells on the 2-cell block of CD-1 mouse zygotes was investigated in comparison with that of CM with rat hepatoma Reuber H-35 cells. In control medium with EDTA, 75.4% of 2-cell embryos developed to the 4- to 8-cell stages. In the same conditions, the BRL Mr  <10000 fraction inhibited the development of 2-cell embryos to the 4- to 8-cell stages (57.7%), although the inhibition by this fraction was weaker than by the Reuber Mr <10000 fraction (19.8%). As a result of reversed-phase column chromatography, a 2-cell stage specific inhibitor of the cleavage of mouse embryos (Fr.B-25), which separated into the Mr <10000 fraction of the Reuber CM, was detected at a low level in the BRL Mr <10000 fraction. On the other hand, the Mr  >10000 fraction of BRL CM accelerated the development of the embryos (90.3%). This beneficial effect was also evident even in the absence of EDTA. RT-PCR analysis revealed that mRNAs encoding the β-A or β-B subunit of activins (Mr ~29000), which are well characterized cytokines that act as releasers of the 2-cell block, were expressed in BRL cells. These results indicate that BRL cells synthesize Fr.B-25 at low levels, and that activins contained in the BRL CM probably contributed to overcoming the 2-cell block of CD-1 zygotes cultured in vitro.},
 pages = {169--174},
 title = {Effect of medium conditioned with rat hepatoma BRL cells on '2-cell block' of random-bred mouse embryos cultured in vitro},
 volume = {17},
 year = {2009}
}