Heterokaryon

A heterokaryon is a cell that contains multiple, genetically different nuclei. A cell with two separate nuclei formed by the experimental fusion of two genetically different cells. (A medical example is a heterokaryon composed of nuclei from Hurler syndrome and Hunter syndrome. Both of these diseases result in problems in mucopolysaccharide metabolism however a heterokaryon of nuclei from both of these diseases exhibits normal mucopolysaccharide metabolism proving that the two syndromes affect different proteins and so can correct each other in the heterokaryon). MedicineNet.com

Another example is the process of sexual reproduction seen in many species of fungi, where cell tips anastomose, exchanging nuclei.

Heterokaryon Гетерокарион 異核共存体