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WHITEFISH MITOSIS
INTERPHASE
The following slides are of the embryos if whitefish (an early stage of embryonic development called the blastula stage). When cells are not dividing, they are in a part of the cell cycle known as Interphase. The nucleus is clearly surrounded by a nuclear membrane, the DNA is visible as chromatin rather than the densely packed chromosomes, and a nucleolus may be visible (see onion slides). There is no sign of the centrosome and the developing spindle.
INTERPHASE INTERPHASE

 
PROPHASE
In prophase , the centrosome duplicates and begins to organize the spindle. On the next page you will see the two centrosomes separate and move to opposite sides of the cell. The nuclear membrane begins to break down and will eventually disappear completely. The DNA condenses to form chromosomes.
PROPHASE PROPHASE
PROPHASE
METAPHASE
In metaphase, the spindle fibers pull on the chromosomes until they are aligned in the center of the cell (along an imaginary line which is referred to as the metaphase plate).
METAPHASE
METAPHASE METAPHASE
METAPHASE METAPHASE
ANAPHASE
In anaphase, the centromeres separate and the chromosomes (which existed as pairs of sister chromatids until they separated) move to opposite poles of the cell.
ANAPHASE ANAPHASE
ANAPHASE ANAPHASE
ANAPHASE ANAPHASE
TELOPHASE AND CYTOKINESIS
Once the chromosomes have been separated, they unwind and return to the form of chromatin. The nuclear membrane reforms and the spindle is broken down. In cytokinesis, the cytoplasm is pinched to form two separate cells.
TELOPHASE TELOPHASE
TELOPHASE TELOPHASE
TELOPHASE TELOPHASE
TELOPHASE TELOPHASE