Time-lapse microscopy of biological systems has provided new and excit
ing information about the dynamics of cellular and developmental event
s. However, these events are often complex and difficult to analyze. T
his paper describes a study in which computation was indispensable for
formulating and evaluating a cellular/developmental hypothesis direct
ly from observations of time-lapse fluorescence images. Previous analy
ses of time-lapse microscopy sequences of Drosophila melanogaster embr
yonic syncytial nuclear cycles 10-13, when the nuclei form an evenly s
paced monolayer at the surface of the embryo, have failed to identify
any pattern in these divisions. However, computational analysis of the
data has provided evidence that the direction of syncytial nuclear mi
tosis is not random, but is clearly influenced by the relative positio
ns of neighboring nuclei. An approximate law governing mitotic directi
on that is based on a scheme that compromises among ''votes'' made by
neighboring nuclei is introduced. (C) 1995 Academic Press Limited