Etude tridimensionnelle du complexe sécréteur plastes–réticulum endoplasmique dans les poils glandulaires d'Hygrophila difformis (Acanthacées)

The general organisation and functioning of the secretory cells of the glandular hairs of Hygrophila difformis show some analogies with previously studied glandular systems of the same type; they differ from the latter, however, in the complexity of organisation of the reticulum – plastid complex.In the undifferentiated cell the plastids have a simple rounded, slightly elongated form; they display no special relationship with the endoplasmic reticulum which, at this stage, is represented by irregularly enlarged cisternae containing a dense substance of fibrous appearance.During the secretory phase, on the contrary, the ultrastructures of the plastids and of the endoplasmic reticulum undergo considerable changes; the latter appears in the form of small tubes arranged parallel to each other and in close contact with the plastids. The plastids themselves take on shapes which, until now, have never been observed in this type of cell and which can only be shown clearly by a three-dimensional reconstruction. This technique, which involves making a series of thin sections, has been applied to secretory plastids for the first time. It gives a faithful picture of their original morphology and the various modes of association possible between the plastids of a given reticulum – plastid complex.