Ultrastructure of tapetum prior to liberation of pollen grains trifoliate orange [Poncirus trifoliata (L.) Raf.]
1999
Mohammad, P. (Ehime Univ., Matsuyama (Japan). Faculty of Agriculture) | Shiraishi, M. | Toda, J.
The tapetal cells in trifoliate orange were studied prior to liberation of pollen grains under light and transmission electron microscopes. The tapetum was glandular or secretory type and consisted of two layered flattened cells immediately below the 2-3 layered elongated parietal cells and anther wall. It surrounded the pollen sacs where numerous pollen grains were embedded freely. Many sporopollenin-like granules appeared throughout the tapetal zone releasing from the territory of tapetum and parietal layers. These granules moved through the intercellular spaces and found their ways towards the pollen grains which were finally absorbed by the bacula of grain walls. The multi-layered rough endoplasmic reticulum appeared near these absorption sites. The tapetal cells were devoid of distinct walls or they had only very thin envelopes. The tapetal cytoplasm contained highly dense, irregularly dense and less dense granules within different vesicles.
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