Morpho-histochemical characterization of salivary gland cells of males of the tick Rhipicephalus sanguineus (Acari: Ixodidae) at different feeding stages: description of new cell types

Abstract

This study describes the changes undergone by cells of the salivary glands of unfed and feeding (at day two and four post-attachment) Rhipicephalus sanguineus males, as well as new cell types. In unfed males, types I and II acini are observed with cells "undifferentiated", undefined 1 and 2 (the latter, with atypical granules), a, c1 and c3; type III is composed of cells d and e; and type IV present cells g. In males at day two post-attachment, type I acini exhibit the same morphology of unfed individuals. An increase in size is observed in types II, III, and IV, as cells are filled with secretion granules. Some granules are still undergoing maturation. In type II acinus, cells a, b and c1-c8 are observed. Cells c7 and c8 are described for the first time. Cells c7 are termed as such due to the addition of polysaccharides in the composition of the secretion granules (in unfed individuals, they are termed undefined 1). Type III acini exhibit cells d and e completely filled with granules, and in type IV, cells g contain granules in several stages of maturation. In males at day four post-attachment, type I acini do not exhibit changes. Granular acini exhibit cells with fewer secretion granules, which are already mature. In type II acini, cells a, b, c1-c5 are present, type III exhibit cells d and e, and type IV contain cells g with little or no secretion. This study shows that in the salivary glands of R. sanguineus males, cells a, c1, and c3 of type II acinus, and cells d and e of type III do not exhibit changes in granular content, remaining continuously active during the entire feeding period. This indicates that during the intervals among feeding stages, gland cells reacquire the same characteristics found in unfed individuals, suggesting that they undergo reprogramming to be active in the next cycle.

Sexual differences in the sialomes of the zebra tick, Rhipicephalus pulchellus

“…Male ticks remain with their mouthparts inside the female's genital pore for several hours after successful spermatophore transfer, perhaps as a mechanism of guarding the females from other males and thus avoid sperm competition [12], but whether they transfer additional fluids into the females is unknown. Histological studies of tick salivary glands have described male-specific alveolus and cells [126-128] that were postulated to assist tick reproduction [13]. Using a differential display approach, differential male salivary gene expression was observed when males were feeding together with and without female conspecific ticks [129, 130].…”

Tick attachment cement – reviewing the mysteries of a biological skin plug system

“…Cement seems to originate from the cell class a‐ of type II acini, and from d‐ and e‐cell classes in type III acini (Sauer et al ., 1995; Coons & Alberti, 1999). Early observations of type IV acini were all from cement‐producing tick species (Fawcett, Binnington & Voigt, 1986), but there are no histochemical indications that they contribute material to the cement cone (Furquim, Bechara & Camargo Mathias, 2010). Indeed, type IV acini are also found in males of Ixodes holocyclus Neumann, 1899, a species which does not produce cement (Moorhouse, 1969) and in which males do not feed (Stone & Binnington, 1986).…”

Structure and function of the foregut and salivary glands of the synanthropic diplopod Urostreptus atrobrunneus (Spirostreptidae)

“…In Ixodidae ticks, which are arthropods in the Acariña order, the salivary glands are essential for the maintenance of life, as well as for the reproductive capacity of individuals because these glands make up a multifunctional organ that allows these parasites to feed (Furquim et al, 2010;Denardi et al, 2011) but also constitutes the major route of transmission of pathogens. The main functions include the absorption of water vapor from unsaturated air by ticks in the wild and the secretion of bioactive proteins and lipid components during feeding (Sauer et al, 2000).…”