Cytoplasmic RNA and nuclear changes detected cytochemically during the degeneration of salivary glands of the tick Rhipicephalus sanguineus (Latreille, 1806) (Acari, Ixodidae) Karim Christina Scopinho Furquim a , Gerva ´sio Henrique Bechara b , Maria Izabel Camargo Mathias a, * a Departamento de Biologia, Instituto de Biocie ˆncias, UNESP, Av. 24 A, no. 1515, Cx. Postal 199, CEP 13506-900 Rio Claro, S.P., Brazil b Departamento de Patologia Veterina ´ria, FCAV, UNESP, Via de Acesso Prof. Paulo Castellane, s/n CEP 14884-900 Jaboticabal, S.P., Brazil Received 16 August 2007; received in revised form 18 October 2007; accepted 18 October 2007 Abstract The present study reports cytochemistry data about salivary glands of females (unfed, engorged, and at day three post-engorgement) and males (unfed, at day seven post-attachment, and at days three and seven post-detachment from the host) of the tick Rhipicephalus sanguineus. The results revealed nuclear changes in engorged females and at day three post-engorgement, and in males in all stages (except unfed). These changes were more prominent in females. Cytoplasmic changes were also observed in cells of all acini of males and females. In types II and III acini of engorged females, nuclear changes were observed in the shape (irregular, with blebs, fragmenting or fragmented), size (enlarged or reduced), and arrangement and condensation level of chromatin (marginal or as blebs). Changes were also detected in nucleoli, regarding their shape (fragmenting or fragmented), size (enlarged), and location (central, marginal or as blebs). Some nucleoli were also compacted or disorganized. In females at day three pos-engorgement, all acini exhibited similar changes to those observed in engorged females. RNA staining was stronger in cells of engorged females than those at day three post-engorgement. In males at day seven post-attachment, cells of types II, III, IV acini presented changes in the size of the nucleus and condensation level of chromatin similar to those of females. The shape of the nucleus was round, irregular or undergoing fragmentation, and the chromatin was located at the margin or throughout the nucleus. The changes in the nucleolus were similar to those of females, regarding size and organization, although round-shaped and in the central location. In males at day three post-detachment, cells of all acini exhibited nuclear changes similar to those of males at day seven post-attachment, in addition to the fragmentation of the nucleolus. At day seven post-detachment, changes were detected in all acini similar to the observed in males at day seven post-attachment. Regarding cytoplasmic RNA, staining was prominent in males at day seven post-attachment and weak in those at day seven post-detachment from the host. In females as well as males, different RNA staining patterns in the cytoplasm and nuclear changes characterized apoptotic cell death. # 2007 Elsevier Ltd. All rights reserved. Keywords: Rhipicephalus sanguineus; Salivary glands; Females; Males; Chromatin; Nucleolus; Apoptosis 1. Introduction Female and male ticks present salivary glands that secrete substances responsible for the attachment of the parasite to the host to allow feeding (Binnington, 1978; Walker et al., 1985; Gill and Walker, 1987). Previous studies on the tick Rhipicephalus sanguineus have demonstrated that the salivary glands undergo periods of intense and low secretory activity. During low activity, the morphology and cytochemistry of these gland cells revealed degenerative features characterizing an atypical type of apoptosis observed in males as well as females of this species, although more prominent in the latter (Furquim, 2007). Data available in the literature indicate that during apoptotic death, nuclear breakdown is one of the first changes observed, characterized by fragmentation, compression, and margination of chromatin, appearance of blebs and finally fragmentation of the nucleus itself (Bowen and Bowen, 1990; Bowen, 1993; Kerr et al., 1995; Ha ¨cker, 2000). www.elsevier.com/locate/micron Available online at www.sciencedirect.com Micron 39 (2008) 960–966 * Corresponding author. Fax: +55 19 35340009. E-mail address: micm@rc.unesp.br (M.I.C. Mathias). 0968-4328/$ – see front matter # 2007 Elsevier Ltd. All rights reserved. doi:10.1016/j.micron.2007.10.022