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The World of Protozoa, Rotifera, Nematoda and Oligochaeta

Ref ID : 6639

Emilia Rota and Pietro Lupetti; An ultrastructural investigation of Hrabeiella Pizl & Chalupsky, 1984 (Annelida). I. Chaetae and body wall organization. Hydrobiologia 334:229-239, 1996

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Specimens of Hrabeiella sp., collected for the first time in Italy (Tuscany), were investigated by transmission and scanninng electron microscopy. Chaetae conform with previous descriptions in light microscopy, but appear considerably different in electron microscopy, as they show an unusual brush-like pattern. The first TEM analysis of the body wall layers was undertaken. The cuticle ultrastructure is similar to that found generally in very small-sized annelids, in that a coarse collagenous grid is absent, but it is peculiar for the paucity of ascending microvilli. Three different types of secretory cells are distinguishable in most of the 12 epidermal glandular blocks occurring around the body circumference. Such blocks regularly alternate with as many muscle fields, each containing four longitudinal fibres. A subepidermal layer of circular muscles is present. The somatopleure is cellular and complete.