title: Ultrastructural changes and a second mode of flagellar degeneration during ageing of Phytophthora palmivora sporangia.
abstract: Ageing of sporangia in Phytophthora palmivora is accompanied by a gradual breakdown of flagella, a transformation of the 'fingerprint' vacuoles, extensive vacuolization of the cytoplasm, accumulation of bundles of microtubules (mastigonemes)contained within cisternae of the rough endoplasmic reticulum, formation of a germination wall lining the inside of the sporangial wall and production of secondary sporangia. The mechanism of flagellar degeneration differs from that observed in directly germinating sporangia. In ageing sporangia and in sporangia induced to germinate directly with germ tubes, there is a close correlation between loss of competence for zoosporogenesis and breakdown of the flagella.
mesh_terms: D004721:Endoplasmic Reticulum / Q000648:ultrastructure; D005407:Flagella / Q000648:ultrastructure*; D005658:Fungi / Q000648:ultrastructure*; D008870:Microtubules / Q000648:ultrastructure; D010838:Phytophthora / Q000502:physiology / Q000648:ultrastructure*; D013172:Spores, Fungal; D013696:Temperature; D013997:Time Factors; D014617:Vacuoles / Q000648:ultrastructure