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The World of Protozoa, Rotifera, Nematoda and Oligochaeta

Ref ID : 4116

Kenneth D. Whitney; Sporocarp Ultrastructure and Development in the Protostelid Cavostelium apophysatum. J.Protozool. 31(2):253-259, 1984

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Ultrastructural observations on the sporocarp of the protostelid Cavostelium apophysatum are presented, including information about the mechanism of sporocarp development. The onset of sporogenesis is marked by cessation of trophic activity and the secretion of a protective sheath. The protoplast gradually molds itself into two distinct zones approximating the shape of the final sporocarp- a hyaloplasmic pre-stalk zone and a globose incipient spore zone. The protoplast in the stalk zone deposits a fibrillar and amorphous stalk acropetally as the stalk protoplast moves into the incipient spore region. The last portion of the stalk to be deposited is the apophysis, a hollow cup-like structure at the stalk apex. Spore wall deposition begins as the stalk nears completion. The wall consists of a single electron-dense layer ornamented with hollow cones and solid projections. The mechanism of sporocarp development in C. apophysatum is compared to the developmental patterns of the protostelids Planoprotostelium aurantium and Schizoplasmodiopsis amoeboidea.