McGurk C, Morris D, Bron J & Adams A (2005) The morphology of Tetracapsuloides bryosalmonae (Myxozoa: Malacosporea) spores released from Fredericella sultana (Bryozoa: Phylactolaemata). Journal of Fish Diseases, 28 (5), pp. 307-312. https://doi.org/10.1111/j.1365-2761.2005.00627.x
First paragraph: Proliferative kidney disease (PKD) is recognized as an economically important disease of salmonid culture in Europe and North America (Hedrick, MacConnell & de Kinkelin 1993). The life cycle of Tetracapsuloides bryosalmonae, the myxozoan parasite that causes the disease, has been partially elucidated and requires a bryozoan host to produce spores that infect fish (Feist, Longshaw, Canning & Okamura 2001). While myxosporean spores are encompassed with hard valves formed from valvogenic cells that subsequently degenerate, the outer surface of the spore of T. bryosalmonae and its sister taxon Buddenbrockia comprises valve cells that retain their cellular integrity and lack hardened valve coats (Canning, Curry, Feist, Longshaw & Okamura 2000). Hence, the class Malacosporea (from the Greek for ‘soft spores') was established to accommodate these organisms. While light- and electron-microscopical studies have revealed many developmental and mature features of these organisms, the precise morphology of the fully formed spores has remained elusive, with only basic features being discernable. Diagrams based on light microscopical examinations have added little to our understanding of how the cells are arranged to form spores.
Journal of Fish Diseases: Volume 28, Issue 5