a. Prophase: In prophase begins the condensation of chromosomes. This condensation is mediated by the action of a protein called condensin, which makes them shorter and thicker. As it condenses, DNA pauses the synthesis of RNA molecules. The filaments, duplicates, are joined at the centromere, and each filament is named chromatoid. Duplicate centrioles migrate to the cell poles and together with fibers form the ester. From the region where the centrioles are located, called the cellular center or centrosome, the mitotic spindle will be formed. The nucleoli disappear and the fragmentation of the library begins. Next, the mitotic spindle microtubules bind to the kinetochore (protein structure located in the centromere region) and carry the chromosomes to the median region of the cell. Its termination is marked by the arrival of chromosomes midway between the cellular poles, that is, in the equatorial plane.
b. Metaphase: The metaphase is marked by the maximum degree of condensation of the chromosomes. The centrioles occupy the opposite poles of the cell and the kinetochore of each chromatid remains attached to the fibers of the mitotic spindle. Arranged in the equatorial region of the cell, the chromosomes form the so-called equatorial plate or metaphysical plate, and each of the sister chromatids turns to each of the cell's poles.
c. Anaphase: In anaphase, the chromatids separate and are called child chromosomes or sister chromosomes. By shortening the fibers of the mitotic spindle, they are pulled to the opposite poles of the cell.
d. Telophase: At this stage, already at the cellular poles, the chromosomes deconcentrate and the formation of new nuclear envelopes begins around each chromosome set, reconstituting two new nuclei. Telophase marks the end of mitosis, preceding the cytokinesis, a process by which the cytoplasm divides and eventually forms two daughter cells.
