Endoconidium Development and Release in the Hyphomycete Phaeotheca fissurella

Abstract

On agar culture media, conidia of Phaeotheca fissurella did not germinate but enlarged to form small mother cells within four da. Division of the small mother cells occurred by development of multilayered, simple septa to form two to several daughter cells. Schizolysis of the cross walls resulted in separation of the daughter cells to form endoconidia which were subsequently released by rupture of the mother cell wall. After a 2-3-week incubation, colonies were elevated and consisted of numerous sclerotic cells. Active endosporulation was restricted to one to several cell layers from the exposed surface of these colonies where large mother cells containing many endoconidia were abundant. Release of the endoconidia from the larger mother cells often was by dissolution of the mother cell wall. The liberated endoconidia were uninucleate and contained well-defined mitochondria, ER, ribosomes, lipid bodies and vacuoles.