Étude ultrastructurale de l'activité des cellules superficielles du thalle des Corallinacées (Rhodophycées)

Abstract

Several species of Corallinaceae, Corallina officinalis Linné, Jania rubens (Linné) Lamouroux, Lithophyllum inerustans Philippi, Lithothamnium lenormandii (Areschoug) Foslie and Mesophyllum liehenoides (Ellis) Lemoine, freshly collected have been examined with electron microscopy in order to study the organic cell wall constitution. The whole external part of the thallus is covered by a ‘cuticle’ which is known to stain deeply with acid fuchsin under the light microscope. The superficial cells which lie just below that cuticle have an uncalcified cell wall at their external pole. With the help of the electron microscopical techniques it can be shown that these superficial cells have a secretory activity. They contain Golgi vesicles of different sizes. The largest among these vesicles are localized close to the top surface of the cell. It seems that they open through the plasmalemma and their content diffuses into the cuticle layer. The TSC cytochemical reaction shows the vesicles to be full of polysaccharidic fibrils and gives details on the structure of the cell wall and cuticle. The process is present even in the marginal initial cells of the hypothallus but is more active in the epithallial cells which can be of two kinds. In the polystromatical epithallia the secretory activity seems to change as the cells age and one can observe the succession of different stages.