Azygosporogenesis in Mucor azygosporus

Abstract

Light microscopic and scanning and transmission electron microscopic observations were obtained on azygosporogenesis in Mucor azygosporus Benjamin. Terminal gametangia are delimited by centripetally growing septa but plasmodesmata maintain cytoplasmic continuity between the azygophores and gametangia. Warts develop as regularly spaced patches of electron-opaque wall material on, and ultimately within, the inner primary wall. The mature complex azygosporangium wall is composed of (1) remnants of the membranous outer primary wall, (2) the ornamented layer of electron-opaque, stellate, confluent warts, and (3) a fibrillar, electron-opaque, tertiary layer. A homogeneous, hyaline azygospore wall (quaternary layer or endospore) with stellate warts is laid down within the azygosporangium. A comparison of the fine structural aspects of zygosporogenesis and azygosporogenesis in the Mucorales is presented.