External factors can significantly influence the rate of mitosis in cells. Growth factors, which are proteins that stimulate cell growth and division, can accelerate the rate of mitosis. For example, the presence of platelet-derived growth factor (PDGF) is known to stimulate the division of fibroblasts during wound healing. Hormones, such as human growth hormone, also play a role in regulating cell division. Environmental conditions like temperature, oxygen availability, and nutrient supply can affect mitotic rates. Higher temperatures often increase enzymatic activities, thereby speeding up cell division. However, extreme temperatures or lack of nutrients can inhibit mitosis. Additionally, chemicals and radiation can either stimulate or inhibit mitosis. For instance, certain chemotherapy drugs intentionally slow down or stop mitosis in cancer cells, while radiation can damage DNA, affecting the cell's ability to divide properly.

The G2 checkpoint, located at the end of the G2 phase of the cell cycle, is crucial for ensuring that cells are fully prepared to enter mitosis. This checkpoint serves several key functions: It checks for DNA damage, ensuring that all genetic material has been accurately replicated without errors during the S phase. If DNA damage is detected, the cell cycle is halted, and repair mechanisms are activated. The G2 checkpoint also ensures that the cell has achieved adequate size and has produced enough proteins and organelles to supply to each daughter cell. Only after passing the G2 checkpoint can a cell proceed to mitosis. This regulation is vital for maintaining genetic stability and preventing the propagation of damaged or incomplete genetic material, which could lead to diseases such as cancer.

Mitosis plays a complex role in the aging process of an organism. On one hand, the ability of cells to undergo mitosis is essential for replacing old, worn-out cells, thereby maintaining tissue function and delaying the aging process. However, as organisms age, their cells' ability to undergo mitosis effectively decreases. This decline can be due to the shortening of telomeres, protective structures at the ends of chromosomes, which become shorter with each cell division. Once telomeres reach a critically short length, cells enter a state called replicative senescence, where they no longer divide. This accumulation of senescent cells contributes to the aging process, leading to decreased tissue repair and regeneration capabilities. Furthermore, the reduced efficiency of the cell's repair mechanisms over time increases the likelihood of mutations during cell division, which can lead to age-related diseases such as cancer. Understanding the relationship between mitosis and aging is crucial for developing strategies to combat age-related degeneration and diseases.

Mitosis ensures genetic stability primarily through the accurate replication and equal distribution of chromosomes to the daughter cells. Each chromosome is duplicated during the S phase of the cell cycle, ensuring that each daughter cell receives an exact copy. During mitosis, particularly in metaphase and anaphase, the chromosomes are aligned and separated with high fidelity, preventing loss or duplication of chromosomes. However, errors can occur, leading to genetic instability. For instance, nondisjunction, where chromosomes fail to separate properly during anaphase, can result in one daughter cell with an extra chromosome and the other with one less, a condition known as aneuploidy. This can cause genetic disorders like Down syndrome. Additionally, mutations during DNA replication, improper spindle formation, or errors in the cell cycle checkpoints can also compromise genetic stability, potentially leading to cancerous growths or cell death.

Cytokinesis, the process of cytoplasmic division that follows mitosis, differs significantly between plant and animal cells. In animal cells, cytokinesis occurs through the formation of a cleavage furrow. This furrow is created by the contraction of actin and myosin filaments that pinch the cell membrane inward, eventually dividing the cell into two. In contrast, plant cells, due to their rigid cell walls, cannot form a cleavage furrow. Instead, a cell plate forms at the site of the metaphase plate. Vesicles from the Golgi apparatus coalesce at the centre of the cell, depositing cell wall materials. This cell plate gradually expands outward until it merges with the cell wall, thereby dividing the cell into two. This process results in the formation of a new cell wall, segregating the two daughter cells. Understanding these differences is crucial as they reflect the unique structural adaptations of plant and animal cells in cell division.