Fine structure of the salivary glands of unfed male Dermacentor variabilis (Say) (Ixodoidea: Ixodidae)


Three types of alveoli were found in the salivary glands of unfed male Dermacentor variabilis. One nongranular and two granule secreting types of alveoli are connected directly or indirectly to the main salivary ducts or its branches. The nongranular alveolus contains several cells, each of which has 3 regions: basal, with many membrane infoldings, mitochondria, and vacuoles; intermediate, with fewer infoldings and more vacuoles; and apical, with few membrane infoldings and mitochondria, some vacuoles, and many microtubules. At least one cell communicates directly with the nonvalvular cuticular alveolar duct. Each of the 2 granule secreting alveoli contains at least 3 granular cell types interconnected by narrow epithelial cells having microtubules and junction specialization with neighboring granule secreting cells. The histochemical properties of granular inclusions are described and their possible functions are discussed. The microvillar apices of the alveolar cells border the alveolar lumen which leads via a thin valvular canal to a conical cuticular guard valve where the base of the chitinous alveolar duct joins the lobular duct. Alveolar ducts, which branch from the main salivary duct, lead to the lobular duct. Each alveolus is innervated by a nerve whose axons, often containing neurosecretory vesicles, enter the alveolus. Synapses were observed between these axons and the apical areas of granule secreting cells.

Publication Title

Journal of Parasitology