[Studies on the septal ultrastructure of Armilaria mellea]

The structure and development of septum in Armillaria mellea were studied under the electronmicroscope. Hyphal septum was developed by inside wall of hyphae in cross direction, leaving a small pore in the center. Then the septal plate arround the pore became swollen, and formed a septal pore apparatus called dolipore septum. With subsequent development of endoplasmic reticulum septal pore caps appeared on each side of the pore. Organelles, such as mitochondrium and Golgi body in hyphal cells were all related with the development of septa. Thin-walled narrow hyphae of the medualla in mature rhizomorph were in a state of dormancy, and their septa were similar to those of the hyphae growing from liquid fermentation. Both of them were short of septal pore caps, but the latter had larger septal pores, the protoplasm flow from cell to cell through the pore was visible, and fusion rate between the hyphae was much higher. The relationship between the structural changes and functions of septa in A. mellea was also systematically discussed in this paper.