Effect of cumulative chemical and mutagenic pollutants during ontogenic development of Poecilia vivipara (Cyprinodontiformes, Poeciliidae)

Abstract

Living in society is a feature of Homo sapiens and this fact gives him the advantage of occupying many biomes. Population increase and technological development brought a growth in the volume of dejects thrown into water sources. Knowledge of biological models that evaluates contamination levels of these sources is the aim of this research. Cells of the branchial epithelium of Poecilia vivipara, popularly known as guaru, modify their behavior in the presence of environmental variations and keep the homeostasis in adverse conditions. Our intention was to know the origin and the differentiation of cell types in the development of the gill and to detect variations of the branchial epithelium in embryos of pregnant females exposed to lead (a cumulative and mutagenic chemical pollutant). Two groups were formed, the control and the experimental group, which was exposed to a solution of 1 ppm lead acetate. Embryos in stages 24, 30 and 36 were observed (Vernier, 1969) and analyzed under light and electronic scanning microscopy. Embryos of the females were quantified and measured. The formation of the arcs, filaments, rays and lamellae gill were registered. In the epithelium, first the chlorine cells differentiated; in stage 36 mucous cells appear in the branchial ray. There were no morphological differences between the groups in the epithelial cells of the gill. Viviparity may be the explanatory factor