Elektronenmikroskopische Beobachtungen an der vegetativen Zelle im auskeimenden Pollenkorn von Oenothera hookeri Torr. et Grey

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Abstract
In accord with the intense activity of the vegetative cell in the germinating pollen grain, the cytoplasm shows a highly organized structure. In structure the vegetative cell differs strongly from the generative cell. Its nucleus is lobed, large invaginations of the cytoplasm into the nucleus being observed frequently. Serial sections show that deep and flat vesicles, which may often broaden to unusually large cisternae, extent through the cytoplasm forming a highly developed endoplasmic reticulum which is continuous with the nuclear envelope. The leucoplasts contain large starch grains and few lamellae. Sometimes, a projection from a leucoplast reaches deeply into another leucoplast. In some leucoplasts and mitochondria concentric stripes are seen, which serial sections show to be the margins of evaginations of the cytoplasm or of another organell. In the numerous mitochondria the inner folds have the form of cristae, tubules are not so frequently seen. The edges of the flattened sacs of the Golgi apparatus expand into vacuoles which seem to separate from the flattened cisternae. Numerous small vacuoles are typical for the vegetative cytoplasm. Relatively large, ringshaped or uniform dark bodies are assumed to be lipid inclusions.