Polymorphism of microtriches in the cysticercoid of Ophryocotyle insignis Lonnberg, 1890 from the limpet Patella vulgata

Abstract

The mature cysticercoid of Ophryocotyle insignis, from Patella vulgata, was examined using transmission electron microscopy. Eight different types of microtriches were present over the tegument of the larval body and microvilli covered the caudal bladder, or cercomer. Rounded, modified microtriches were present on the external surface of the bladder enclosing the cysticercoid. Microtriches lining the retraction chamber ranged from small triangular projections having an electron-dense ridge along the anterior margin but having no shaft, to more typically shaped, larger microtriches having a cytoplasmic base, electron-dense shaft, and an electron-dense ridge along the anterior margin of the base. The scolex tegument had large robust microtriches which, in transverse section, had many projecting flanges. The microtriches on the rostellum were long and slender. Long, thin microtriches were present amongst the small spines on the suckers and short microtriches were found on the unspined areas of the suckers. Possible functions for the different types of microtriches are suggested and the significance of microvilli on the cercomer is discussed.