Genèse des différents organites de la spore uninucléée d’ Amblyospora culicis (Protozoa, Microspora)

Abstract

The elaboration of the uninucleate spore of Amblyospora culicis (Protozoa, Microspora) is described by transmission electron microscopy. The first event of this sporogenesis is the formation of the spore wall. Some metabolic granules elaborated in the pansporoblastic vacuole fuse and set as a wall on the outside of the sporont plasma membrane. This wall appeared as two electron dense layers separated by a transparent one. During sporogenesis this wall thickens and becomes complex. In the mature spore, it is composed of an inner electron transparent endospore and an outer exospore exhibiting 5 structurally different layers. The polar filament is elaborated in the sporoblast. It is firstly a coil in the posterior half of the sporoblast; then its anterior end moves to reach a granular body which appeared in the anterior part of the sporoblast. This granular body elaborates the polar cap and becomes the polar sac. The last organelle differentiated is the polaroblast. It is elaborated from an amorphous structure which appeared under the polar sac of the young spore. In this structure numerous membranous cisternae appear. The first become parallel and flattened sacs, while the last stay swollen vesicles. When the sporogenesis is over, the spore possesses a thick wall, an abruptly constricted polar filament and a large polaroplast consisting of membranous flattened sacs and swollen vesicles.