Formation of pollen in the anther of Lilium. II. The function of the surrounding tissues in the formation of pollen and pollen wall

In the Lilium anther a peritapetal and tapetal membrane are made by the tapetal cells. During the young microspore stage the pro-orbicules receive a matrix of mainly carbohydrates similar to that of the sexine. The plasma-membrane of the tapetal cells forms membrane-like lamellae. During the vacuolization of the microspore the orbicule diameter increases. In the channels made by the endoplasmic reticulum the globules of sporopollenin are produced. The lipid inclusions accumulate and globules containing carotenoid increase in the plastids. Both elements fuse and form the “Pollenkitt” during degeneration of the tapetal cell. Some sporopollenin globules fuse and form a second generation of orbicules. The cell of the middle layer next to the tapetal cell contains lipid granules. The other four cells of the middle layer lose their starch at the stage of the young microspore and after mitosis the lipid granules are produced. As a source for nutrients in the loculus the starch of the middle layer cells has an important function. An interaction model is schematically presented.