L'infrasTruttura di Dunaliella Salina

Abstract

The ultrastructure of Dunaliella salina. — The ultrastructure of Dunaliella salina is described. Its structural organisation is rather similar to that previously reported for other Volvocales. The lack of a cellulosic wall is confirmed; the protoplast is bounded only by the monolayered plasma membrane which covers also the flagella. The conspicuous cup-shaped chloroplast fills up the whole back part of the cell and its terminal part is close to the anterior pole: consequently all the other cellular organelles are confined in its deep anterior cavity. The pyrenoid is located in the back part of the chloroplast: communication between the pyrenoid and the surrounding chloroplast is established by a system of paired lamellae. The droplets of carotenoids which form the eyespot are not stacked in regular order. The Golgi apparatus is located in the anterior part and is formed by two conspicuous dictyosomes. A great number of vesciculae, perhaps formed by the dictyosome, are crowded around the insertion of the two flagella. Evidence for the existence of an endoplasmic reticulum is uncertain. Two unknown structures are observed and their morphological organisation is described.