A new description of the reproductive system of Schistosoma mansoni (Trematoda: Schistosomatidae) analyzed by confocal laser scanning microscopy

Abstract

Classical schemes of the adult Schistosoma mansoni reproductive system have been described. In our study, whole adult worms derived from unisexual or mixed infections and stained with carmine chlorine were virtually and tomographically analyzed under confocal laser scanning microscopy. We found that: (1) there were morphological differences in the ovary, vitteline glands and testicular lobes between specimens derived from unisexual or mixed infections; (2) there was always a single lobed ovary (three or four lobes), presenting differentiation from the anterior to the posterior lobes, where the most mature oocytes were located; (3) the proximal segment of oviduct was connected to an ampullary dilatation, full of tailed spermatozoa, characterizing a seminal receptacle; (4) there was no long vitelline duct, but a short one that begins at the end of the proximal region of the vitelline gland; (5) long cells of Mehlis' gland placed radially around the ootype were not observed. Otherwise, the ootype was only lined by thick cuboidal epithelial cells with plaited bases and nuclei with flabby chromatin, making a clear distinction from the uterine epithelium. This morphological feature suggests that each cell represents a gland. (6) In coupled males, the specimens located inside the gynaecophoric canal had smaller testicular lobes, suckers, and body length and width when compared to their partners. Our results show that the reproductive system does not follow a unique pattern within flatworms. Due to its better resolution, confocal laser scanning microscopy, using a reflected mode with tomographic sections, allows new interpretations, modifying the adopted and current descriptions of the internal morphological structures of S. mansoni adult worms.

Development of Schistosoma mansoni worms in mice analyzed by bright field and confocal microscopy

“…As a consequence, these structures could be atrophied or have their size reduced. In addition, female's suckers are not muscular as males, the tegumental tubercles, if any, are spineless and unremarkable in texture (Neves et al 2005). We may reasonably infer that all these features are from evolutive traits.…”

“…Earlier studies have evidenced two testicular lobes and a narrow uterus (Clegg 1965). Examination of whole-mount preparations using confocal microscopy has helped characterize novel details of the reproductive system of S. mansoni, modifying the adopted and current descriptions of the internal morphological structures (Neves et al 2005). Although this lobes might not be perceptible by bright field microscopy, if present the tomographic analysis by confocal microscopy should have identified these structures due to its better resolution (Machado-Silva et al 1998).…”

Characterization of the cGMP-dependent protein kinase SmcGK1 of Schistosoma mansoni

“…During treatment periods for 2-6 days in vitro we monitored worms at a daily basis and, in addition, performed CLSM for morphological analysis as described before (Machado-Silva et al 1998, Neves et al 2005, Beckmann et al 2010a. Monitoring revealed a slomo effect on adults, which we first observed after 3 days of treatment, increasing in intensity until day 6.…”

“…Morphological analyses were done according to a confocal laser scanning microscopical (CLSM) method described in earlier studies (Machado-Silva et al 1998, Neves et al 2005. In short, adult worms were fixed for at least 24 hours in AFA (alcohol 95%, formalin 3%, and glacial acetic acid 2%), stained for 30 minutes with 2.5% hydrochloric carmine (Certistain , Merck), and destained in acidic 70% ethanol.…”

Assessment of Akodon cursor (Rodentia, Sigmodontinae) as permissive host to Schistosoma mansoni infection: morphology of adult worms

“…The images were transferred from the LSM computer to Microsoft ImagerTM and Corel Draw 6.0TM for final contrast, brightness and gamma correction adjustments and then printed using a Codonics NP 1600TM printer (Machado-Silva et al 1998). The reproductive organs (testicular lobes, supernumerary testes, seminal vesicle, ovary, oocytes, seminal receptacle, vitelline glands, ootype and uterus), tegument, digestive system and excretory system were examined (Neves et al 2005). In males, tegument thickness measurements were always taken from the region below the second testicular lobe, whereas measurements from females were taken from the area adjacent to the ventral sucker.…”