Scenes of cell division

ABOVE -- A photomicrograph made using fluorescent light microscopy shows a one-cell stage Caenorhabditis elegans (roundworm) embryo undergoing cell division. Microtubules (green) are rigid protein polymers that organize, capture and move chromosomes (blue) made up of DNA. Chromosomes are in two groups, which are being pulled by microtubules towards opposite poles of the bipolar spindle. The microfilament cytoskeleton (red) is at the cell cortex just underneath the cell membrane. These longer, more flexible protein polymers must be organized into a "cleavage furrow" that pulls a circumferential ring of the cell surface into the center of the cell, ultimately dividing the single parent cell into two daughter cells at the end of cell division -- each with one complete set of chromosomes and genes. The organization and constriction of the cleavage furrow happens slightly later. (CLICK on image to access a downloadable high-resolution version)

ABOVE -- Photo shows just microfilament cytoskeleton at the cell cortex. In the top and middle embryos, microfilaments become organized into a loose network in the cleavage furrow. This sequence shows one cell dividing to produce two daughter cells, going from the one-cell stage of embryogenesis to the 2-cell stage. (CLICK on image to access a downloadable high-resolution version)

BACK TO STORY