Ultrastructural Aspects of the Development of Fibres From the Flowering Stem of Lolium Temulentum L.

Summary Fibres develop from initially elongated cells with a large proportion of cytoplasm containing many ribosomes, relatively few, but large, mitochondria, proplastids, Golgi bodies and either several small vacuoles or one central vacuole. During cell elongation the central vacuole enlarges and the cytoplasm forms only a thin lining except at the fibre tips. At this stage the ribosomes are present as polysomes and associated with the endoplasmic reticulum as rough ER(RER). The number of Golgi bodies apparently increases and there are both electron transparent vesicles of various sizes and small vesicles with an electron dense core. Lomasomes and inclusions between the wall and the plasmalemma are seen at this stage. Increase in cell wall thickness is associated with an increase in the number of Golgi bodies with large vesicles and also those vesicles with an electron dense core. Wall thickening is also accompanied by the appearance of many microtubules parallel to the long axis of the cell adjacent to the plasmalemma. Even in a well developed inflorescence axis bearing ripening grains there is still visible cytoplasm in the majority of the fibre cells.