Perithecium development in Podospora tetraspora and Podospora vesticola

Perithecium development in Podospora tetraspora and Podospora vesticola begins as ascogenous cells which are quickly enveloped by growth of sterile hyphae to form the young perithecium. At a later stage these tissues begin to differentiate, the outer peridial pseudoparenchyma becomes pigmented and the ascus initials are embedded in small-celled pseudoparenchyma which fills the centrum. A surrounding jacket of large pseudoparenchymatous cells (=jacket paraphyses) encases the centrum. The agent(s) which brings about the formation of the periphyses also affects the upper cells of both the pseudoparenchymatous jacket tissue and central pseudoparenchyma, such that the end cells disassociate from one another and the jacket tissue assumes a free-ended appearance. At maturity, the asci grow up between central elongated pseudoparenchymatous tissue which becomes obliterated during this process, and may serve a nutritive function. The jacket paraphyses remain, encasing the asci and forming an inner lining to the perithecium. Perithecium development in these two closely related fungi differs from that which has been described for some related species.