Efeito do cloreto de cádmio sobre as gônadas de girinos de rãs-touro (Lithobates catesbeianus)

• Ano de defesa: 2014
• Autor(a) principal: Rizzi, Gisele Miglioranza [UNESP]
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Estadual Paulista (Unesp)
• Palavras-chave em Português: Amphibians; Anfíbio; Toxicologia ambiental; Morfologia (Animais); Histoquimica; Rã touro; Gonadas; Girino; Cadmio
• Link de acesso: http://hdl.handle.net/11449/108675

A study about the effects of cadmium chloride (CdCl2) on tadpoles at Gosner stage 25 exposed for 4 and 16 days, to dosage environmentally accepted by National Council on the Environment (CONAMA) for the water classes 1 and 2, was performed. The results showed significant morphological and functional changes. On the ovaries of individuals exposed for 4 days, acceleration in the initial gametogenesis was observed, evidenced by the increased incidence of the number of oocytes in stages I, II and III and increased incidence of micronucleoli, which demonstrates high RNA synthesis. The histochemical and immunohistochemical techniques revealed no relevant changes caused by this trace metal. On the ovaries of individuals exposed for 16 days, acceleration in the initial gametogenesis was also observed, as reported by individuals exposed for 4 days. Immunohistochemistry showed overexpression of HSP70, indicating oxidative stress or physiological adaptive response to CdCl2. On the testicles of individuals exposed for 4 days, there were cases of anatomical changes, cell death, changes in somatic cell death and resorption of the germ cells, degeneration of gonadal tissue, adipogenesis and nonfunctional polygonadism. As noted on the ovaries for this period of exposure, the histochemical and immunohistochemical techniques revealed no relevant changes caused by this trace metal, showing basal expression. On the testes of individuals exposed during 16 days, the acceleration of testicular development was observed, with early primary spermatocytes organizing to form the primary seminiferous ducts, mixed polygonadism, as well as sex reversal. Immunohistochemistry showed no significant differences between the control and exposed groups regarding the expression of HSP70, however it is notable that this expression is below that observed in the group exposed for 4 days. For these reasons, the research shows that the parameters used by CONAMA as doses...