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Animal Mitosis

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This video was made by Conly Rieder, Richard Cole, and Jennifer Waters. Drs. Rieder and Cole work at the Wadsworth Center for Cell Biology in Albany, NY, and Dr. Waters is from the University of North Carolina at Chapel Hill. This sequence appears in the video CELLebration, edited by R. Fink, published by the American Society for Cell Biology and Sinauer Associates, Inc.

Newt lung epithelial cells are extremely flat and transparent, and have large chromosomes. Small pieces of lung tissue were dissected from Taricha granulosa newts, and cultured on coverslips for 7-10 days. Mitotic cells were filmed using Nomarski differential interference optics, which give the chromosomes their nice fat 3-D look. Time compression was 1:60. The diameter of the nucleus is approximately 50 um, and individual chromosomes are on the order of 20 um long.

This is a normal mitosis. The diploid chromosome number is 22. The nuclear envelope breaks down, and the spindle forms in regions of clear cytoplasm. The tendency is for each chromosome to attach first to microtubules from the closest pole, and then subsequently attach to the pole farther away. After a chromosome forms this bipolar attachment, it is moved to the spindle equator. Anaphase begins when the sister chromatids separate, and each moves to its respective pole. The resulting daughter nuclei will have genetically identical, full chromosome complements.