Reference work entry
Latin: spiculum = thorn.
The spicules are characteristic copulatory structures of male nematodes ( Nematodes/Figs. 12 and 13). In most nematodes there are two spicules, which often differ in length and shape, but in some species only a single spiculum (Latin = peak, arrow) is found ( Nematodes/Fig. 13). The spicules are needle shaped and consist of thick cuticular material which surrounds a cytoplasmatic core with nerve processes. The nerve endings are covered by cuticular material. In many species the spicule wall is bent to form a hollow needle with an opening at its base and tip. The spicules are formed in a dorsal sac of the cloaca called the spicular pouch. The spicules can be moved back and forth by accessory muscles and during copulation they are inserted into the female vulva. A thickening of the dorsal wall of the spicular pouch, the gubernaculum, stabilizes the protruded spicule. Additional copulatory structures are found in some groups ( Nematodes/Reproductive...
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