A scanning electron microscopic study of the external features of perithecium development in Sordaria humana

Abstract

The external features of perithecium development in Sordaria humana have been examined with the scanning electron microscope. Variations in specimen preservation were evident after using different preparative procedures. Different stages of perithecium development were correlated with culture age. The developmental sequence was as follows. An ascogonial coil was initiated as a side branch of a vegetative hypha and became enclosed by enveloping hyphae originating from one or more locations. The enveloping hyphae of the resultant spherical protoperithecium gave rise to fringe hyphae and, after cohesion, to the protoperithecium peridium. The neck was first evident as a bulge on the fruit body surface. Ostiolar pore formation soon followed. Neck extension primarily involved the differentiation of periphyses, lining the ostiolar canal, into the coherent cells of the neck peridium. A positive neck phototropism resulted from the differential growth of periphyses. Neck hyphae often grew from the base of the neck peridium. Neck development was sometimes terminated by ostiolar pore occlusion. The different cellular elements observed have been classified into two basic types: (i) discrete hyphae and hyphallike elements which exhibit a pronounced longitudinal type of growth pattern; and (ii) coherent elements which arise by the cohesion of adjacent hyphae or hyphallike elements.