Ultrastructural aspects of ascosporulation in Arthroderma quadrifidum (=Trichophyton terrestre).

The ultrastructural features of developing and mature ascospores were delineated after mating Arthroderma quadrifidum on pablum cereal agar. Incipient ascospores each contained a granulated nucleus bounded by a nuclear envelope while presumptive ascospore cytoplasm was bounded by a double membrane and resided in glycogen-rich epiplasm of the ascus. Mature ascospores contained nuclei and mitochondria while the ascus epiplasm still retained abundant inclusions. The ascospore wall demonstrated the presence of heterogeneous material between the plasmalemma and the outer spore membrane which appeared smooth.