Molecular Info®

Molecular Info® Copy Right © 2001 Institute of Molecular Development LLC

Blastomeres arising from the first cleavage division have distinguishable fates in normal mouse development. Karolina Piotrowska, Florence Wianny, Roger A. Pedersen and Magdalena Zernicka-Goetz The Development, October 2001, 128: 3739-3748 . Two-cell stage blastomeres have a strong tendency to develop into cells that comprise either the embryonic or the abembryonic parts of the blastocyst. Moreover, the two-cell stage blastomere that is first to divide will preferentially contribute its progeny to the embryonic part. There is a boundary zone adjacent to the interior margin of the blastocoel that is populated by cells derived from both earlier and later dividing blastomeres. The majority of cells that inhabit this boundary region are derived from the later dividing two-cell stage blastomere that contributes predominantly to the abembryonic part of the blastocyst. Thus, at the two-cell stage it is already possible to predict which cell will contribute a greater proportion of its progeny to the abembryonic part of the blastocyst (region including the blastocyst cavity) and which to the embryonic part (region containing the inner cell mass) that will give rise to the embryo proper.