The hooked dikaryotic tip of an * ascogenous hypha. Its two nuclei divide simultaneously and the resulting four daughter nuclei are partitioned by two septa into three cells. The middle cell contains two genetically different nuclei and the apical and basal cells either side contain one nucleus each. The apical cell bends round to fuse with the basal cell, thus reestablishing the dikaryotic condition in both cells resulting from the cell division. The middle cell, now at the tip of the ascogenous hypha, develops into an ascus. The cell below may extend and go on to form another crozier. Similarities between this process and the * clamp connections of certain basidiomycetes have led to the suggestion that basidiomycetes evolved from ascomycetes.  |
