Telophase marks the final stage of mitosis, the process by which a single parent cell divides its genetic material into two new daughter cells. This phase ensures each new cell receives a complete and identical set of chromosomes. Telophase reverses many structural changes from earlier stages, preparing the cell for physical separation.
Chromosomal and Nuclear Transformations
As telophase progresses, the chromosomes, which were condensed during earlier stages, begin to uncoil and decondense. They transition back into a less compact, thread-like form known as chromatin, characteristic of interphase. This decondensation is necessary for the cell to resume its normal genetic functions, such as gene expression and DNA replication, in interphase.
New nuclear envelopes reform around each set of chromosomes at opposite poles of the cell. This reassembly creates two distinct nuclei within the parent cell. The nuclear envelope reforms from fragments of the parent cell’s nuclear membrane and vesicles from the endoplasmic reticulum that coalesce around the decondensing chromosomes. This process re-establishes the selective barrier between the genetic material and the cytoplasm.
The nucleoli reappear within each newly formed nucleus. The nucleolus, a dense region within the nucleus, is responsible for ribosomal RNA synthesis and ribosome assembly. Its reappearance signals the resumption of ribosome production, fundamental for protein synthesis in the emerging daughter cells.
Spindle Disassembly and Cellular Division
The mitotic spindle, which segregated chromosomes to opposite poles, begins to disassemble during telophase. Its microtubules depolymerize, completing their task in chromosome movement. While most spindle microtubules depolymerize, some may remain to assist in cytokinesis.
Cytokinesis, the physical division of the cytoplasm, begins during or after telophase. This process ensures cellular contents are apportioned into two separate entities, forming two distinct daughter cells. The mechanism of cytokinesis differs between animal and plant cells due to structural variations.
In animal cells, cytokinesis involves the formation of a contractile ring composed of actin and myosin filaments. This ring assembles just beneath the plasma membrane at the cell’s equator. The contraction of this ring creates an inward constriction, known as a cleavage furrow, which deepens, pinching the cell into two daughter cells.
For plant cells, which possess a rigid cell wall, cytokinesis proceeds differently. Instead of a contractile ring, Golgi-derived vesicles containing cell wall materials are transported to the cell’s center, where they fuse to form a structure called a cell plate. This cell plate grows outward from the center, eventually fusing with the existing parent cell walls, thereby dividing the cell into two. The culmination of telophase and cytokinesis results in two genetically identical daughter cells, each ready to begin its own life cycle.