Cover photograph (Copyright © 2008, American Society for Microbiology. All Rights Reserved.): Contents of cleistothecia (fruiting bodies) from Aspergillus nidulans strains expressing either the Aspergillus nidulans MatA or the Aspergillus fumigatus Mat1-2 HMG box mating type protein. Shown are ascogenous hyphae and asci at various stages of development. Asci include the following: young asci during meiosis and prior to ascospore cell delineation; colorless asci after delineation of a random octad of ascospores; asci containing an octad of immature ascospores with lightly pigmented cell walls; and asci with mature, red-pigmented ascospores. (See related article on page 1029.)