Orientation of mitotic spindles during the 8- to 16-cell stage transition in mouse embryos.

• Main Authors: Nicolas Dard, Sophie Louvet-Vallée, Bernard Maro
• Format: Article
• Language: English
• Published: Public Library of Science (PLoS) 2009-12-01
• Series: PLoS ONE
• Online Access: http://europepmc.org/articles/PMC2781390?pdf=render

BACKGROUND:Asymmetric cell divisions are involved in the divergence of the first two lineages of the pre-implantation mouse embryo. They first take place after cell polarization (during compaction) at the 8-cell stage. It is thought that, in contrast to many species, spindle orientation is random, although there is no direct evidence for this. METHODOLOGY/PRINCIPAL FINDINGS:Tubulin-GFP and live imaging with a spinning disk confocal microscope were used to directly study spindle orientation in whole embryos undergoing the 8- to 16-cell stage transition. This approach allowed us to determine that there is no predetermined cleavage pattern in 8-cell compacted mouse embryos and that mitotic spindle orientation in live embryo is only modulated by the extent of cell rounding up during mitosis. CONCLUSIONS:These results clearly demonstrate that spindle orientation is not controlled at the 8- to 16-cell transition, but influenced by cell bulging during mitosis, thus reinforcing the idea that pre-implantation development is highly regulative and not pre-patterned.