The Septal Pore and Other Ultrastructural Features of The Pyrenomycete Sordaria Fimicola

SUMMARY

Two types of septa are present in the pyrenomycete Sordaria fimicola.The simple, ascomycetous septum (characterized by an opening usually associated with Woronin bodies, or with vesicles and a few profiles of endoplasmic reticulum) is found in non-ascogenous structures. In contrast, the ascogenous elements show a structurally more complex septal pore. The pore rim is covered by a deposit that extends out along both sides of the septum for a very short distance. This deposit reduces the effective pore size. Clumped or stacked membrane profiles are associated with the pore deposit and radiate outwards in the cytoplasm of both ascogenous cells related by the common septum. The complex septum was found to be related to the special nuclear pairing stage preceding karyogamy and meiosis and has its organization maintained from crozier proliferation throughout ascus development.