A characteristic form of growth seen in dividing dikaryotic hyphae of basidiomycete fungi (see illustration). Before cell division occurs the two nuclei divide simultaneously and at the same time a backward-pointing side branch develops. One of the daughter nuclei moves into this while another daughter nucleus of different genetic constitution moves down the main fila- ment away from the hyphal tip. Two cross walls are then formed, one across the main filament, so separating off the other two nuclei in the hyphal tip, and the other across the side branch. The wall between the branch and the subapi-cal cell then dissolves so the nucleus in the side branch can pass through to join the remaining daughter nucleus. This process has apparently developed to avoid the random movement of daughter nuclei, which could lead to the production of homokaryotic cells. See also crozier.  Stages in the formation of a clamp connection. |
