The dikaryon is a nuclear feature which is unique to some fungi (the alga Derbesia is an exception). Compatible cell-types can fuse cytoplasms (plasmogamy). When this occurs, the two nuclei of two cells pair off and cohabit without fusing (karyogamy). This can be maintained for all the cells of the hyphae by synchronously dividing so that pairs ar...
A pair of nuclei that associate and divide simultaneously. 
A hypha with two nuclei. ... (09 Oct 1997) ... 
A fungal compartment (often called a cell but fungi are generally better regarded as being coenocytic) containing two genetically distinct haploid nuclei.