Three-dimensional analysis of laser scanning confocal microscope sections reveals an array of microtubules in the cleavage furrow of sea urchin eggs

Our recent observation that microtubules (MTs) are required for completion of division (abscission) led us to analyze MT organization during cytokines is. Although many studies of MTs in sea urchin eggs have been done, compute r-aided analysis of optical sections described herein reveals a new MT asse mblage, which we call furrow MTs. This assemblage comprises bundles of MTs that lie in the cleavage furrow. Furrow MTs become apparent when the furrow has progressed approximately one-third of the way through the egg and pers ist to abscission. Furrow MTs are 8-24-mum long and are across the base of the cleavage furrow. Acetylated tubulin is localized primarily in the furro w suggesting a distinct MT population. Three-dimensional analysis of optica l sections suggests that furrow MTs are spatially distinct from midbody and astral MTs.