| Popis: |
Development of the centrum in Monosporascus cannonballus is of the Xylaria type. The perithecium begins development as a curved, multinucleate branch; the ascogonium, from an assimilative hypha. The ascogonium coils, becoming looser as it elongates. Ultimately it is septate, and each segment has one to several nuclei. Branches from the parent hypha and probably from neighboring hyphae develop to cover the ascogonium. These covering hyphae give rise to the perithecial wall cells and to the plectenchyma of the centrum. Paraphyses, apically free from their inception, develop from the plectenchyma before asci are produced. Ascogonial segments give rise to short ascogenous hyphae, which produce croziers terminally. Asci arise from the croziers. After karyogamy and precocious synapsis, two meiotic divisions are followed by a mitotic division. The haploid chromosome number is eight. Some or all of the eight nuclei formed are incorporated into the single ascospore, the remainder being visible in the residual cyto... |
