Cell Biology

One fascinating problem in the field of cell biology is the spatial control of cell division: how do cells regulate the size and shape of their daughter cells? In this ascidian embryo, fixed at the 16 cell stage, 3 molecules have been flouroescently labelled: DNA in blue, microtubules in green, and a surface polarity protein called aPKC in red. In most cells of the embryo the spindle is centered, but in the two cells at the bottom, one pole of the spindle (green) is pulled towards a cortical polarity struct.