Fine structure of the vagina, accessory glands, uterus, oviducts and Gene's organ in the unfed tick, Ornithodoros (Pavlovskyella) erraticus (Ixodoidea: Argasidae).

Abstract

The fine structure of the reproductive system of the unfed female Ornithodoros (Pavloskyella) erraticus is described. The vagina consisting of vestibular (VV) and cervical (CV) regions is formed of a single epithelial layer lined with cuticle and surrounded by muscle layers. Epithelial cells of VV show no signs of activity, while those of CV have structural features of transporting epithelia. A pair of tubular accessory glands opening at the junction of the two vaginal regions consist of a layer of microvillate columnar cells containing rough endoplasmic reticulum; this is possibly involved in the formation of colloidal material which presumably coats the egg surface during its passage through the vagina. The bilobed uterus opening into the cervical vagina secretes material that is possibly responsible for the release of sperm from the endospermatophore. The paired oviducts joining the uterine lobes anteriorly have distinctive distal (DO) and proximal (PO) parts as well as 'ampullae' (AMP) at their junction. DO cells contain many lysosome-like structures which probably play a role in breaking down some sperms ascending to the ovary. Cells of AMP are packed with rickettsia-like Wolbachia, while those of PO contain a few granules. Gene's organ, present in female ticks only, consists of a stalk and two horns of epithelium lined internally by a cuticular layer. Bundles of microtubules are detected in the horn cell cytoplasm. This organ functions to waterproof the eggs with a waxy layer just before they are deposited.