Ultrastructural observations on the anterior adhesive apparatus in the monogeneans Dactylogyrus amphibothrium Wagener, 1857 and D. hemiamphibothrium Ergens, 1956.

The light microscope and the transmission electron microscope have revealed that the anterior adhesive apparatus of Dactylogyrus amphibothrium and that of D. hemiamphibothrium are similar and composed of three kinds of gland cell, one producing rod-shaped bodies (secretion S1), one producing spherical bodies (S2), and the third producing electronlucent vesicles (S3). In the cytoplasm of G1 gland cells each rod-shaped body is enclosed by a single layer of microtubules but no microtubules are associated with S2 and S3 bodies. The possible functions of these microtubules are discussed. The ducts which extend anteriorly from all three kinds of gland cell converge on and open into six adhesive sacs, situated ventrally on the distal extremities of the head lobes. Each adhesive sac is supplied with at least one gland duct from each type of gland cell and is lined by a special tegument bearing dense microvilli and a few cilia which may have a sensory function. It has been shown that during the attachment of the head region, these sacs are everted to expose the enclosed microvilli and duct openings and secretions S1 and S2 are extruded.