Current literature

Abstract

The sequence of intracellular transitions leading to the formation of γ particles during zoosporogenesis was examined by electron microscopy of synchronous cultures of Allomyces macrogynus and semisynchronous cultures of Catenaria anguillulae. In Allomyces the first identifiable progenitors of the γ matrix are 60-nm-diameter electron-opaque granules found within cisternae of rough ER. These particles appear during the first 30 minutes after the induction of sporogenesis. By the completion of papilla formation these “subunits” increase in number and size to form spherical structures ca. 133 nm in diameter. At the beginning of nuclear cap formation the 133-nm-diameter electron-opaque granules fuse to form larger spheres averaging 216 nm in diameter. These structures occur singly and in groups which fill the smooth-surface cisternae containing them. Toward the end of nuclear cap formation the granules fuse to form the 500-nm-diameter γ body. In Catenaria the first progenitors of γ particles are 45-nm-diameter electron-opaque granules with transparent centers that appear within swollen cisternae of tubular smooth ER. These granules form larger aggregates which fuse after cleavage to form the fully differentiated γ matrix. The γ particles of Catenaria are ca. 250 nm in diameter, which is smaller than the ca. 500-nm-diameter γ particles of Allomyces macrogynus and Blastocladiella emersonii.