The picture shows a number of asci diverging towards the centre of the perithecium that contains many ascospores that have already been released. The ascus wall is thin and appears to consist of a single layer. Some asci possess a slight invagination that encircles the tip, suggesting the presence of some structural modification for spore release. Arising from the same layer as the asci are delicate, thread-like structures. These may represent some form of sterile hairs or are the remains of asci that have discharged their spores.
Sterile hairs line the neck canal of each perithecium.
Sixteen, and perhaps up to 32 elongate ascospores, are present in each ascus. The special significance of the Rhynie chert ist that structures are preserved in great detail. The oldest fossil ascomycetes. Nature, v. 399, p. 648.