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Figure 1 | Frontiers in Zoology

Figure 1

From: The role of ventral and preventral organs as attachment sites for segmental limb muscles in Onychophora

Figure 1

Position and structure of the ventral and preventral organs in adult onychophorans. Light micrograph (A) and scanning electron micrographs (B–E). Anterior is up in all images. (A) Overview of the ventral body surface in an anesthetised specimen of Epiperipatus sp. 1 (Peripatidae). Note the ventral (arrows) and preventral (arrowheads) organs, which appear as bright segmental spots along the ventral midline. (B) Ventral and preventral organs in Epiperipatus biolleyi (Peripatidae), which are widely separated, as in all other peripatids. (C) Inner surface of a moulted cuticle of Principapillatus hitoyensis (Peripatidae) showing the median sclerotized ridges of the ventral and preventral organs. (D) Ventral and preventral organs in the peripatopsid Metaperipatus inae that, in contrast to the peripatids, appear as a unitary structure. (E) Genital region in E. biolleyi. Note that the genital opening/pad lies between the ventral and preventral organs (labelled by an artificial colour), as in other species of onychophorans studied (cf. Additional file 1). Abbreviations: dp, dermal papilla; gp, genital opening/pad; pv, preventral organ; rd, median ridge; sl, median slit; vo, ventral organ. Scale bars: 1 mm (A), 25 μm (B), 30 μm (C), 50 μm (D), and 100 μm (E).

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