A Review of the Ultrastructure and Ontogeny of Some Angiosperm Pollen

Abstract

The common mode of angiosperm pollen ontogeny, as exemplified in Campanula persicifolia, C. rotundifolia and C. rapunculoides, is reviewed. A comparison is made with that seen in Eleocharis (Cyperaceae), in which the tetrad generally gives rise to a single viable pollen grain, the remaining cells degenerating. The intracellular distribution of, and fine structural changes in the various organelles are related to the morphogenetic stages of pollen wall formation, viz. the callose, primexine template and probacula (the first exine). The tissue surrounding the pollen is briefly described.