Telophase is the final stage of mitosis, the process cells use to divide their copied chromosomes into two identical sets. It’s essentially mitosis in reverse: everything that was disassembled at the start of division gets rebuilt. The nuclear envelope re-forms around each group of chromosomes, the chromosomes uncoil back into their loose, spread-out form, the nucleolus reappears, and the spindle fibers that pulled the chromosomes apart break down. By the end of telophase, the cell contains two fully formed nuclei, and physical separation of the cell itself is nearly complete.
Where Telophase Fits in the Cell Cycle
Mitosis has four stages: prophase, metaphase, anaphase, and telophase. During prophase, chromosomes condense and the nuclear envelope dissolves. In metaphase, chromosomes line up along the cell’s center. Anaphase pulls the two copies of each chromosome toward opposite ends of the cell. Telophase is the cleanup and rebuild phase, where the cell essentially reverses the dramatic changes of prophase and transitions back toward a resting state.
One common point of confusion is the relationship between telophase and cytokinesis, the physical splitting of one cell into two. These are not the same event, but they overlap heavily. Cytokinesis typically begins during late anaphase and is nearly finished by the time telophase ends. So while telophase handles the nuclear reconstruction, the cell’s cytoplasm is being pinched or partitioned at the same time.
Rebuilding the Nuclear Envelope
One of the most important jobs during telophase is wrapping each set of chromosomes inside a new nuclear membrane. At the start of mitosis, the old nuclear envelope was broken into small membrane fragments. Now those fragments, along with membrane from the cell’s internal transport system, are recruited back to the surface of the clustered chromosomes.
This reassembly happens in stages. First, membrane pieces are targeted to the chromosome surface. Then those pieces fuse together into a continuous double membrane. As the membrane closes, nuclear pore complexes are inserted into it. These pores are the gateways that will control what enters and exits the nucleus once the cell returns to its normal working state. Certain inner membrane proteins attach directly to the chromosome surface, anchoring the new envelope in place. Without this coordinated process, the new nuclei couldn’t function properly.
Chromosomes Uncoil Into Chromatin
Throughout most of mitosis, chromosomes are tightly coiled into compact, rod-like structures. This condensation makes them easier to move without tangling, but it also makes their DNA inaccessible. Genes can’t be read while chromosomes are packed this tightly.
During telophase, the chromosomes decondense, gradually loosening back into the diffuse, thread-like form called chromatin. This is what allows the cell to resume reading its genes and producing proteins once division is complete. The process is driven in part by the loss of protein complexes called condensins that held the DNA in its compacted state. As these complexes release from the chromatin and the nuclear envelope reforms around it, the DNA rapidly unwinds. The nucleolus, a structure inside the nucleus responsible for building the cell’s protein-making machinery, also reappears at this point as the genes encoding ribosomal RNA become active again.
Spindle Fibers Break Down
The mitotic spindle, the scaffold of protein filaments that pulled chromosomes to opposite poles, is no longer needed once the chromosomes have arrived at their destinations. During telophase, spindle microtubules are rapidly disassembled. The filaments that connected the two poles of the spindle depolymerize from their tips, and the protein subunits are recycled back into the cell’s supply of building materials. Multiple pathways work together to ensure this breakdown is thorough: some actively chop apart the filaments, others prevent them from regrowing. The whole structure disappears within minutes.
What Drives These Changes
All of the events in telophase are triggered by the same signal: a sharp drop in the activity of a key enzyme complex that had been driving mitosis forward. This complex (called MPF, or maturation-promoting factor) was responsible for phosphorylating, or chemically tagging, hundreds of proteins at the start of mitosis. Those tags caused the nuclear envelope to break apart, chromosomes to condense, and the spindle to form. When MPF activity falls at the transition into telophase, those proteins are dephosphorylated, and the cell reverses course. The nuclear envelope reassembles, the chromosomes decondense, and the microtubules return to their normal interphase arrangement.
Plant Cells vs. Animal Cells
Telophase itself looks similar in plant and animal cells: both rebuild nuclear envelopes, decondense chromosomes, and disassemble spindles. The major difference is in the cytokinesis happening alongside it.
In animal cells, a ring of contractile protein filaments forms just beneath the cell surface at the equator. This ring tightens like a drawstring, pinching the cell membrane inward until the cell is squeezed into two. The first visible sign is a pucker called the cleavage furrow.
Plant cells can’t do this because they have a rigid cell wall. Instead, they divide from the inside out. Small vesicles carrying cell wall materials are transported along leftover spindle microtubules to the center of the cell, where they fuse together to build a new wall called the cell plate. This plate grows outward until it reaches the existing cell wall, splitting the cell in two. The structure guiding this process, called the phragmoplast, begins assembling in late anaphase and continues working through telophase.
Telophase in Meiosis
Meiosis, the type of cell division that produces sperm and egg cells, includes two rounds of division, and telophase occurs at the end of each one.
In telophase I, the cell has separated homologous chromosome pairs (not individual chromosomes). Each resulting nucleus contains half the original chromosome number, but each chromosome still consists of two joined copies. The nuclear envelope reforms, chromosomes decondense, and the cell divides into two daughter cells.
In telophase II, those joined copies have been pulled apart, much like in regular mitosis. The result is four cells, each with a single copy of every chromosome. The same events occur: nuclear envelope reassembly, chromosome decondensation, spindle breakdown, and cytokinesis. The critical difference is the outcome. Mitotic telophase produces two genetically identical cells. Meiotic telophase II produces four genetically unique cells, each with half the original chromosome count.
What Happens When Telophase Goes Wrong
If the nuclear envelope fails to reassemble correctly, particularly if nuclear pores don’t form properly, the new nuclei can’t regulate the flow of molecules in and out. This disrupts gene expression and protein production. Cells missing functional pores in their nuclear envelope are essentially non-viable.
If cytokinesis fails while telophase completes normally, the result is a single cell with two nuclei, a condition called binucleation. These cells contain double the normal chromosome count. When they attempt to divide again, the extra chromosomes often distribute unevenly, producing daughter cells with abnormal chromosome numbers. This kind of error is a hallmark of many cancers, where cells frequently show chaotic chromosome counts and failed divisions.