Ultrastructural changes to P. myriotylum as a result of exposure to E. adenophorum oil extracts were observed using TEM. The control mycelia of P. myriotylum grown in the absence of oil extracts showed the cell wall to be uniform; the cytoplasmic matrix was abundant; and organelle-rich cytoplasm was present that included mitochondria (m), golgi apparatus (g), vacuole (v), liposome (l) and nucleus (n) (Fig 6). All of those organelles have normal and uniform structures (Fig 6A–6C). In the presence of oil extracts at 40 μg/ml, the most conspicuous ultrastructural change observed was the lack of liposomes in the cytoplasmic matrix. The vacuoles, nucleus and mitochondria had the same appearance as the control hyphae, except there were fewer of them. At a higher concentration of 60 μg/ml, the oil extracts caused more obvious ultrastructural alterations: The cells were abnormally shaped, the cytoplasmic organelles were no longer present, cytoplasmic matrixes were absent, the cell wall was thinner and cell wall debris was observed (Fig 6G–6I). At a concentration of 80 μg/ml oil extracts, the cell ultrastructure damage was even more apparent as organelles and most cytoplasmic inclusions were completely absent, leaving only mostly empty cavity cells (Fig 6J–6L).