No abstract

SYNOPSIS. This study augments our knowledge of several ultrastructural features of Encephalitozoon cuniculi and provides evidence that this species is disporous. We support Cali's view that Encephalitozoon is distinct from Nosema and should be treated as a valid genus. We compare these with 2 other disporous genera, Glugea and Perezia, and conclude that Glugea is also distinct but Perezia is a junior synonym of Nosema.

SYNOPSIS. Cell hypertrophy tumors (xenomas) associated with Glugea weissenbergi n. sp. frequently occur under the peritoneum (parietal or visceral) of Apeltes quadracus (Mitchell) near Solomons Island, Maryland. The microsporidan is similar to the type species, G. anomala (Moniez, 1887) Gurley, 1893, but has larger spores. Its fine structure corresponds with the basic pattern revealed by other authors in various species of Nosematidae. A concept of spore morphogenesis, in which the polar filament primordium is 1/2 of the nuclear isthmus present during division of the sporont, is elaborated and its implications discussed. The membrane systems of the Glugea and host cell components appear to be continuous with one another, this being an indication that the membranes are all furnished by the host cell. Lacking mitochondria and (apparently) a Golgi apparatus, Glugea is, when considered apart from the membrane system which is common to it and the host cell, a very simple organism, consisting of very little besides the genome. The simplicity of the Glugea, its very high degree of structural and physiological integration with the host cell, and the transformative development of the host cell all suggest an analogy with certain viruses.