Mitosis

Mitosis is divided into four distinct stages: prophase, metaphase, anaphase and telophase. During prophase, the nuclear envelope disperses, replicated chromosomes condense, and the two sister chromatids become attached at a site called the centromere. At metaphase, duplicated chromosomes become aligned in a single plane. At anaphase A, the sister chromatids separate and begin to migrate to the poles. At anaphase B, the sister chromatids continue to migrate toward the poles and the microtubules of the spindle elongate. During telophase, the sister chromatids reach the poles, the nuclear envelope re-forms and the chromosomes decondense. Cytoplasmic division usually begins in anaphase and is complete by the end of telophase.

Slide #112: Whitefish Mitosis

The whitefish embryo has been stained with hematoxylin and eosin (H&E). Cells are dividing mitotically. Moreover, since cells are dividing asynchronously, there are examples of cells at all stages of the cell cycle. Assess nuclear envelope breakdown, chromosome condensation, mitotic spindle development, and location of condensed chromosomes in the whitefish mitotic cells. On the basis of these parameters, identify and determine the distinguishing features of cells in prophase, metaphase, anaphase (A and B) and telophase.