Discovery of Stretch Receptor Organs in Nematodes–Structure, Arrangement and Functional Analysis

Filamentous organs, termed metanemes and interpreted as stretch receptor organs, have been discovered in nematodes of the order Enoplida. They have not been found in species of 11 other nematode orders. According to light microscopical observations, a metaneme consists of a 5–15 μm long scapulus, a 20–400 μm long frontal and a 30–170 μm long caudal cuticularized filament; the latter is lacking in some taxa. Metanemes are arranged serially in the lateral epidermal cords; they are parallel or at an angle of 10–30° to the longitudinal body line. The function of metanemes is likely to coordinate the serpentine movement and to control the actual body volume.