Stages of Mitosis

Stages of Mitosis

Mitosisis a continuous process. The process is completed by a complex method.   According to the sequence and stages, this continuous process is dividedinto five stages. The stages are:

(1) Prophase, (2) Pro-Metaphase,  (3)Metaphase,Anaphase and (5)Telophase.

1. Prophase: At this stage, the nucleus swells up.

Chromosomes begin to be dehydrated. As a result, the chromosomes gradually become shorter and thicker.

Then they are visible under microscopes. At the end of this stage nucleolus and nuclear membrane become disappear.

2. Pro-Metaphase : At the beginning ofthis stage. the fibrous protein converse to form a bi-polar spindle apparatus. Each chromosome is then become attached to a fibre of the spindle apparatus by its centromere. Each fibre of the spindle apparatus is called spindle fibre. The fibre to which the chromosomes are attached is called traction fibre. As they are attached with the chromosomes so they also called chromosomal fibre. In animal cell aster rays are radiated from centrioles present at two poles.

3. Metaphase : Chromosomes are arrangedat the equatorial plane of the spindle. The centromere of each chromosome remains at the equatorial plane and the two arms are placed towards two poles. At this stage, the chromosomes become maximum thick and short. Two chromatids of a chromosome become maximum thick and short. Two chromatids of a chromosome become clearly visible and the centromere is divided in to two parts.

4. Anaphase : Two separate chromatids ofa chromosome move towards the opposite pole of the spindle apparatus. Centromere goes ahead at the movement of the chromatids towards the pole and the arms follow them. when the daughter chromosomes reaches near the poles the anaphase stage ends.

5. Telophase: Daughter chromosomes take position at two opposite poles.Chromosomes  gradually  take  water  andbecome elongated, thin and long. Nuclearmembranedevelops encirclingthechromosomes.  Nucleolusreappears  at  thesecondary constrictionof    theSatchromosome. Spindle apparatus disappears.

At  the  end of  this  stage,gradually  acellwall develops at the equatorial region of the cell.

As a result, the mother cell divides into two daughter cells. In case of animal cells, instead of formation of cell wall the cell membrane is constricted inwardly and the cell divides into two.