A heterokaryon is a cell that contains two or more genetically distinct nuclei within a single cytoplasm. This phenomenon often occurs in fungi, where different strains can fuse together, allowing for genetic exchange and diversity. Heterokaryons can also be found in some plant and animal cells, particularly in certain experimental or pathological conditions. In the context of cell biology, heterokaryons are important for studying genetic interactions and cellular processes. They can provide insights into how different genetic backgrounds influence traits and behaviors, making them valuable in research areas such as genetics and biotechnology.