Micromorpholgical studies on senescence process of hyphae in cultivated Auricularia auricula-judae
木耳菌丝老化过程的微形态学研究

Process of senescence in hyphae of cultivated Auricularia auricula-judae was observed microstructurally and ultrastructurally. In 30d after inoculation, the hyphae were uniform and well-knit; the cell wall was smooth. Under transmission electron microscope, the cells were intact, with abundant inclusions and all organelles were normal. In 60d part swelling hyphae were observed and the color of hyphae were darker. Under transmission electron microscope, the cell wall was unconsolidated, and the mitochondria and vacuole were swollen; nuclei were irregularly swollen, and nucleoli disappeared, and then granules and vesicles increased. Meanwhile, a few electron-dense granules appeared, which indicated the senescence of hyphae. In 90d membrane of part of the nuclei was broken, and a great amount of lipid granules, vesicles and electron-dense granules were observed. The cell wall was futher loose. In 120d lots of hyphae became fractured and the color was much darker. Under transmission electron microscope, collapsion of cell wall and disintegration of cytomembrane system were observed, and part of cell organelles, such as mitochondria, disappeared. In 150d most of hyphae were completely fractured and lost their shapes, and the cytomembrane and cell inclusions were almost disappeared, but part of collapsed cell walls were observed. It was indicated that the senescence process of Auricularia auricula-judae hyphae was irreversible, which developed from individual to whole cells gradually.