New Insights into the Gametogenesis of Biomphalaria glabrata (Mollusca, Gastropoda, Pulmonata): Implications for Histopathological Assessment

Abstract The reproductive system has a fundamental role in population dynamics and several reproduction strategies have been shaped by the environment over time. Many environmental pressures are generated by releasing pollutants, as endocrine disruptors, that can affect the reproductive system of individuals, among them invertebrates. The freshwater snails Biomphalaria spp. are used as biomonitor in several ecotoxicological studies; however, there are few studies about gametogenesis and morphology of reproductive snail cells, which could be used as a new biomarker. In this sense, the current study aims to characterize Biomphalaria glabrata gametogenesis, bringing new histomorphometric parameters for germinative cells. Results showed that the hermaphrodite tissue is formed by several acini with simple pavement epithelium with germinative and somatic cells. Oogenesis was classified into five developmental stages (OI to OV) according to diameter, nucleus area, total area, and follicular cell development, and then classified into previtellogenic and vitellogenic oocytes. The spermatogenesis was classified into spermatogonia (Spg), spermatocytes (Spc) and spermatids that were subdivided into five stages (Spt I to Spt V) according to cytoplasm losing, and nucleus spiralization along with Sertoli cells development. Thus, the present study highlights the gametogenesis of B. glabrata with new histomorphometric parameters, which can be an important tool for ecotoxicological and molluscicidal developmental further studies.

Ovary histology and quantification of hemolymph proteins of Rhipicephalus (Boophilus) microplus treated with Melia azedarach / Histologia do ovário e quantificação de proteínas na hemolinfa de Rhipicephalus (Boophilus) microplus tratado com Melia azedarach

This study aimed to analyze ovary histology and quantify total protein in the hemolymph of Rhipicephalus (Boophilus) microplus females treated with hexane extracts from green fruits of Melia azedarach. Eight engorged females were immersed in the extract at 0.25% concentration, and eight in water containing 5% acetone (control). The females were dissected 72 hours after treatment, and the ovaries were weighed and subjected to standard histological techniques. The total protein concentration was measured in the hemolymph of 200 females, of which 100 were treated as described above and 100 served as a control. In the treated group, ovary weight reduction and predominance of immature oocytes were observed. In addition, there were decreases in the diameters of the cytoplasm and germ vesicle of the oocytes in the treated group, compared with the controls. The protein concentration in the hemolymph was higher in the treated group than in the controls. The morphological changes observed in the treated ovaries included: presence of vacuolization; alteration of oocyte morphology, which changed from rounded to elongated; deformation of the chorion; and disorganization of the yolk granules. These results demonstrate the action of M. azedarach fruit extracts on R. (B.) microplus oogenesis.

Este estudo foi desenvolvido, visando analisar a histologia do ovário e quantificar as proteínas totais na hemolinfa de fêmeas de Rhipicephalus (Boophilus) microplus tratadas com extrato hexânico de frutos verdes de Melia azedarach. Oito fêmeas ingurgitadas foram tratadas por imersão com o extrato na concentração de 0,25%, e oito com água contendo 5% de acetona (controle). As fêmeas foram dissecadas 72 horas após o tratamento e os ovários foram pesados e submetidos a técnicas histológicas padrões. A concentração total de proteína foi mensurada na hemolinfa de 200 fêmeas, sendo 100 tratadas como descrito anteriormente e 100 como controle. Foi observada redução do peso dos ovários, predomínio de ovócitos imaturos e houve diminuição nos diâmetros do citoplasma e da vesícula germinal dos ovócitos do grupo tratado em comparação ao controle. A concentração de proteína na hemolinfa foi mais alta no grupo tratado que no controle. As alterações morfológicas observadas nos ovários tratados foram a presença de vacuolizações, alteração da morfologia dos ovócitos que mudaram de redondos para alongados, deformação do córion e desorganização dos grânulos de vitelo. Estes resultados demonstram a ação do extrato de M. azedarach na ovogênese de R. (B.) microplus.