Mitosis, light micrograph

Light micrograph of a muntjac deer (Muntiacus sp.) cell in the prometaphase stage of mitosis (nuclear division). Mitosis is the formation of two daughter nuclei from one parent nucleus. At prometaphase the chromatin has condensed but there is not yet complete attachment of the chromosomes to the spindle. At metaphase sister chromatids, which are made of DNA (deoxyribonucleic acid), line up along the centre of a cell. During the next stage, anaphase, the chromatids are separated to opposite ends of the cell by spindles. The spindles attach to the chromosomes via protein structures known as kinetochores (brown dots). Two identical chromatids make up one chromosome, so each cell retains a copy of the parent cell's genetic information. Silver stain., by DR. JUAN F. GIMENEZ-ABIAN / SCIENCE PHOTO LIBRARY