multinucleaat

Multinucleate, or multinucleaat, describes cells or cytoplasms that contain more than one nucleus. This condition arises through two main routes: cell fusion, where multiple cells merge their plasma membranes and cytoplasm to form a single structure with multiple nuclei; and division of nuclei without cytokinesis, a process known as endomitosis or karyokinesis without cytokinesis, which increases nuclear content within one cell.

In animals, multinucleate cells are common in several tissues. Skeletal muscle fibers are classic examples, formed by the fusion of many myoblasts into long, multinucleated syncytia that coordinate contraction. Osteoclasts, the bone-resorbing cells, are another well-known multinucleate type, arising from fusion of macrophage lineages. The placenta contains multinucleated cells in the layer called the syncytiotrophoblast, which forms a barrier and interface with maternal blood. Viral infections can also induce multinucleation when viral proteins trigger fusion of neighboring cells, creating syncytia.

In other kingdoms, multinucleation occurs in coenocytic fungi, where hyphae lack septa and house numerous nuclei within a continuous cytoplasm. Plasmodial slime molds, such as Physarum, maintain a single multinucleate cytoplasmic mass called a plasmodium that streams cytoplasm and coordinates growth and locomotion.

Functional implications include rapid distribution of enzymes and metabolites across large cytoplasmic volumes, synchronized cellular processes, and efficient resource sharing. Regulation of gene expression and organelle distribution can be more complex in multinucleate cells, and such cells can be involved in various pathologies or developmental processes depending on context.