AAT Bioquest

What are the differences between open and closed mitosis?

Posted November 30, 2023


Basis of differentiation

Open mitosis

Closed mitosis


Open mitosis is the separation of chromosomes subsequent to nuclear envelope breakdown (NEBD)

Closed mitosis is the separation of chromosomes and  spindle formation without NEBD


In multicellular organisms

Occurs in lower eukaryotes (typically in fungi)


The nuclear envelope disintegrates prior to the chromosomes segregating  

Chromosome division occurs within the cell nucleus

Significance of evolution

Open mitosis has been altered several times during evolution

Is the oldest mechanism of eukaryotic cell division

Spindle formation

Spindle fibers form within the nucleus

Spindle fibers form outside of the nucleus 

Nuclear membrane

The nuclear membrane disintegrates and then re-forms around 2 sets of segregated chromosomes

The nuclear membrane remains intact

Additional resources

The cell biology of open and closed mitosis

Cell Cycle Assays

Cell Meter™ Fluorimetric Live Cell Cycle Assay Kit *Green Fluorescence Optimized for Flow Cytometry*