Anatomy and ultrastructure of the reproductive systems ofAcarus siro (Acari: Acaridae)

Abstract

Anatomy and ultrastructure of the female and male reproductive system in Acarus siro L. were investigated by light and electron microscopy. The female system consists of paired ovaries of nutrimentary type in which oogonia and oocytes are connected by bridges with a large central cell. The oviducts empty into the uterus, which passes into preoviporal duct lined by cuticle, and opening as a longitudinal slit (oviporus). An elongated accessory gland composed of one type of secretory cell is located along each oviduct. The copulatory opening occurs at the posterior margin of the body and leads, via the inseminatory canal, to the receptaculum seminis, consisting of the basal and saccular part. Both inseminatory canal and basal part of receptaculum seminis are lined by cuticle, whereas the wall of the sac is formed by cells covered only by long, numerous microvilli. The basal part of the receptaculum seminis joins the ovaries via two lumenless transitory cones. The male reproductive system contains paired testes, in which spermatogonia tightly surround the central cell. The proximal part of the paired vasa deferentia serves as a sperm reservoir, while the distal one has a glandular character. An unpaired, cuticle-lined ejaculatory duct opens into the apex of the aedeagus. The single accessory gland is located asymmetrically at the level of, or slightly posterior to, coxae IV. The structure of the genital papillae, which are topographically related to the genital opening in both sexes, is also briefly described.

Male nutritional history affects female fecundity in a male-dimorphic mite: Evidence for a nuptial gift?

“…To our knowledge, this is the first reported observation suggestive of a nuptial gift transfer in mites. In Acarus siro, a species related to the bulb mite (Dabert et al 2010), Witaliński et al (1990) identified morphological structures in the female reproductive tract through which females could absorb nutritional contributions. If female bulb mites have similar structures, they could use these to absorb nutrients in seminal fluid (e.g.…”

“…Simmons and Parker 1989) to obtain valuable substances (Bownes and Partridge 1987;Markow 1988;Edvardsson 2007;Gwynne 2008) or digest superfluous (Sivinski 1980) or non-reproductive (Silberglied et al 1984;Swallow and Wilkinson 2002) sperm cells. To unequivocally determine the existence of nuptial gift transfer in the bulb mite, morphological studies to identify structures in the female's anatomy that take up nutrients from seminal fluid (as in Witaliński et al 1990), and physiological studies that follow the fate of potential nutrients in the seminal fluid (e.g. Bownes and Partridge 1987), are required.…”

Fine structure and probable function of ring organs in the mite Histiostoma feroniarum (Acari: Actinotrichida: Acaridida: Histiostomatidae)

“…However, in other Acaridida, even those also living in aquatic niches (Naiadacarus arboricola: Acaridae) (Fashing, 1988), as well as in the freshwater oribatid Hydrozetes (Löwenfeld, 1987;Alberti and Löwenfeld, 1990), the modified cuticle is not perforated. Canals have also not been observed in the modified cuticle of genital papillae in other terrestrial Actinotrichida (Neomolgus littoralis: Bdellidae; Acarus siro: Acaridae) (Alberti, 1979;Witaliń ski et al, 1990). The disc cuticle in Histiostoma feroniarum is not perforated and closely resembles the cuticle of Claparède organs and genital papillae in Naiadacarus arboricola and Acarus siro (Acaridae) (Fashing, 1988;Witaliń ski et al, 1990), since it is practically homogeneous, electron-dense, and sepa-rated from the surrounding unmodified cuticle by an electron-dense material of the epicuticle.…”

“…Canals have also not been observed in the modified cuticle of genital papillae in other terrestrial Actinotrichida (Neomolgus littoralis: Bdellidae; Acarus siro: Acaridae) (Alberti, 1979;Witaliń ski et al, 1990). The disc cuticle in Histiostoma feroniarum is not perforated and closely resembles the cuticle of Claparède organs and genital papillae in Naiadacarus arboricola and Acarus siro (Acaridae) (Fashing, 1988;Witaliń ski et al, 1990), since it is practically homogeneous, electron-dense, and sepa-rated from the surrounding unmodified cuticle by an electron-dense material of the epicuticle. Interestingly, when slides for LM are prepared after the special staining with the Lugol solution and safranin, heavily stained discs can be easily removed and displaced, e.g., by shifting a coverslip, which supports a different composition of the disc and relatively weak connection between both cuticular compartments.…”

“…Similar chambers, more or less evident, have also been reported in other species investigated to date. A transparent chamber was found in the genital papilla of Acarus siro (Witaliń -ski et al, 1990) as well as in the Claparède organ of Naiadacarus arboricola (Fashing, 1988). In Algophagus pennsylvanicus, the chamber in the axillary organ is filled with an amorphous extracellular substance (Fashing, 1984).…”