Karyology During Conidiogenesis in Gliomastix Murorum: Light Microscopy

Abstract

Light microscopic observations of nuclear behavior (karyology) during conidiogenesis in the long, narrow phialides of Gliomastix murorum (Corda) Hughes are presented and discussed. Nuclei were observed mostly in a submedian position in phialides. The onset of mitosis was signalled by an increase in the size of nuclei and by the appearance of numerous chromatinic granules (chromosomes?). The number of chromatinic granules appeared to decrease, while the chromatin was arranged in the characteristic “double track” associated with somatic nuclear divisions in hyphomycetes. Transverse separation of the “double track” arrangement produced two daughter chromatinic masses which stained intensely, were small, and moved apart. Separation of daughter chromatinic masses (nuclei) appeared to be largely a function of migration of distal daughter nuclei several micrometers toward phialidic apices; the submedian position of proximal daughter nuclei was maintained. Upon movement of migrating distal daughter nuclei into conidial initials, conidia were delimited septally. Conidial nuclei remained condensed, while daughter nuclei remaining in phialides decondensed (i.e., enlarged and stained less intensely), thereby entering interphase. Repeated, single nuclear divisions and migrations were correlated with repeated conidial development. Karyological events described herein were compared with other published studies of both phialidic and non‐phialidic species, and a “phialidic pattern” of nuclear behavior was suggested as a possibility. But, apparently a non‐phialidic pattern cannot yet be suggested.