Ultrastructure of the male reproductive accessory glands in the medfly Ceratitis capitata (Diptera: Tephritidae) and preliminary characterization of their secretions D. Marchini a , G. Del Bene b , L. Cappelli a , R. Dallai a, * a Department of Evolutionary Biology, University of Siena, Via A. Moro 2, I-53100 Siena, Italy b Istituto Sperimentale per la Zoologia Agraria, Via Lanciola 12/a, I-50125 Firenze, Italy Received 29 October 2002; accepted 23 December 2002 Abstract The morphology and the ultrastructure of the male accessory glands and ejaculatory duct of Ceratitis capitata were investigated. There are two types of glands in the reproductive apparatus. The first is a pair of long, mesoderm-derived tubules with binucleate, microvillate secretory cells, which contain smooth endoplasmic reticulum and, in the sexually mature males, enlarged polymorphic mitochondria. The narrow lumen of the gland is filled with dense or sometimes granulated secretion, containing lipids. The second type consists of short ectoderm-derived glands, finger-like or claviform shaped. Despite the different shape of these glands, after a cycle of maturation, their epithelial cells share a large subcuticular cavity filled with electron-transparent secretion. The ejaculatory duct, lined by cuticle, has epithelial cells with a limited involvement in secretory activity. Electrophoretic analysis of accessory gland secretion reveals different protein profiles for long tubular and short glands with bands of 16 and 10 kDa in both types of glands. We demonstrate that a large amount of accessory gland secretion is depleted from the glands after 30 min of copulation. q 2003 Elsevier Science Ltd. All rights reserved. Keywords: Insect reproduction; Seminal fluid; Male reproductive system 1. Introduction In insects, male reproductive accessory glands, meso- derm- or ectoderm-derived (Leopold, 1976; Davey, 1985), produce secretions with a variety of functions, including contribution to the seminal fluid and activation of the spermatozoa (Davey, 1985; Chen, 1984). Moreover, in some insects, they are involved in the building of spermatophores for sperm transfer to the female (Viscuso et al., 2001). It has been reported that virgin females undergo two major characteristic changes following copulation: an increase in fecundity and a reduction in sexual receptivity (Chen, 1984). Additional female responses such as oviduct contraction and oocyte maturation have been established (Gillott, 1996; Eberhard, 1996). Many data concur that an active factor or factors inhibiting female receptivity and stimulating egg laying originate in the male accessory glands or in the secretory cells present in the ejaculatory duct (Raabe, 1986). It is generally accepted that male seminal products in insects have diverse, far-reaching effects on female behaviour and physiology in many different species. How this occurs, and the mechanism determining the cascade of female responses is more difficult to establish; however, it is now suggested that the common route is through the walls of the female reproductive tract and into the body cavity. Once seminal fluid constituents enter the female haemolymph, the target organ seems to be the female nervous system (Chen, 1984; Gillott, 1996). As a result of this action two effects, inhibition of remating and induction of oviposition, can be observed. In Aedes aegypti two different protein com- ponents of seminal fluid were responsible for inhibition of female receptivity and enhancement of egg laying (Fuchs and Hiss, 1970; Young and Downe, 1982). Accessory gland secretions which caused females to be refractory to remating were also reported for Glossina morsitans (Gillott and Langley, 1981); Musca domestica (Riemann et al., 1967); Mayetiola destructor (Bergh et al., 1992); and Lucilia cuprina (Smith et al., 1989). A sex peptide, secreted by the male accessory glands of D. melanogaster, is responsible for stimulating the female’s egg laying rate and depressing her receptivity to mating (Chen et al., 1988; Kubli, 1992, 1467-8039/03/$ - see front matter q 2003 Elsevier Science Ltd. All rights reserved. doi:10.1016/S1467-8039(03)00003-3 Arthropod Structure & Development 31 (2003) 313–327 www.elsevier.com/locate/asd * Corresponding author. Tel.: þ 39-577-234413; fax: þ 39-577-234476. E-mail address: dallai@unisi.it (R. Dallai).