Ascus cytology and ascocarp development in Achaetomiella virescens

The development of ascocarp and the nuclear behaviour during the development of ascus and ascospores was studied in Achaetomiella virescens. The ascocarp development in A. virescens begins with the formation of deeply staining ascogonial coils as lateral branches of the vegetative hyphae. As these coils develop into multicellular, multinucleate ascogonia, they are surrounded by a pseudoparenchymatous envelope. This ascocarp initial in later stages of development gets differentiated into a central sporogenous core and wall layers. The central sporogenous core breaks and becomes a loose mass of multinucleate cells. Some of these multinucleate cells become meristematic and give rise to ascogenous cells at the base of developing ascocarp. Asci are formed from these ascogenous cells by croziers. Four divisions result in binucleate ascospores and each mature ascospore has a single nucleus. The haploid number of chromosome is 6 (n=6).