MOVIE 1.

Contact between the C blastomere and the ABar blastomere directs the spindle orientation of ABar division in a wild-type C. elegans embryo. (Left) Contact between the C blastomere (membrane near contact outlined in blue) and the ABar blastomere (membrane near contact outlined in green). The focal depth (18 μm) of greatest contact is shown. (Right) Shortly after contact between the C and the ABar blastomeres, the mitotic spindle of the ABar blastomere (right line) is shifted toward the contact, resulting in a cell division that is perpendicular to the orientation of division of the neighboring ABpr blastomere (left line). The focal depth is 7.5 μm. (To view movie, see doi: 10.1101/pdb.prot5542 online at www.cshprotocols.org.)