By Melissa Mayer | Updated Aug 30, 2022
During the M phase of the cell cycle, duplicated chromosomes segregate into two daughter nuclei. The process relies on centrosomes at each pole and the spindle apparatus, composed of specialized microtubules that pull sister chromatids apart. Finally, cytokinesis completes the division, producing two genetically identical cells.
While reading about mitosis can be informative, observing the stages under a microscope provides a vivid, tangible experience. With simple preparations, you can view each phase in real time—ideal for classroom demonstrations, science fairs, or personal exploration.
The cell cycle consists of interphase (G1, S, G2) and mitosis (M phase). Interphase prepares the cell for division: growth, DNA replication, and checkpoint surveillance. At the end of interphase, the cell is ready to enter mitosis, where it will undergo four distinct stages—prophase, metaphase, anaphase, and telophase—before cytokinesis.
In prophase, chromatin condenses into distinct, X‑shaped chromosomes. The nuclear envelope breaks down, and the nucleolus disappears. Cytoskeletal microtubules reorganize into the bipolar spindle apparatus, anchored at the centrosomes now moving toward opposite poles.
Microscopically, early prophase shows long, thick DNA strands with a visible nucleolus. Late prophase reveals the centrosomes at cell poles and the emerging spindle fibers.
Chromosomes align along the metaphase plate, the cell’s central plane, each attached to spindle fibers. Because each chromosome is already duplicated, the pairs of sister chromatids are poised for separation.
Under the microscope, you’ll see a row of chromosomes centered in the cell, flanked by spindle fibers radiating toward the poles—an image of tension as the cell prepares to split.
During this brief phase, the sister chromatids separate and are pulled to opposite poles by the shortening of spindle fibers. The cell elongates, and the two chromosome sets begin to form distinct nuclear territories.
Early anaphase displays chromosomes moving apart; late anaphase shows them at opposite ends of the cell, often with the nascent cleavage furrow beginning to form.
Telophase marks the re‑formation of nuclear envelopes around each chromosomal set and the decondensation of DNA. Spindle fibers disassemble, and the cell membrane (or cell wall in plant cells) starts to constrict between the two halves.
When telophase completes, cytokinesis finishes the division, yielding two independent daughter cells each with a complete set of chromosomes.
To view mitosis stages, fix cells in a suitable stain (e.g., Giemsa or DAPI), mount on slides, and examine under a light or fluorescence microscope. With proper staining, the distinct phases become readily distinguishable, allowing you to capture the dynamic process of cell division.
