Abstract:
Excessive agriculture, transport and mining often lead to the contamination of valuable water resources. Communities using this
water for drinking, washing, bathing and the irrigation of crops are continuously being exposed to these heavy metals. The most
vulnerable is the developing fetus. Cadmium (Cd) and chrome (Cr) were identified as two of the most prevalent heavy metal water
contaminants in South Africa. In this study, chicken embryos at the stage of early organogenesis were exposed to a single dosage of
0.430 mM physiological dosage (PD) and 430 mM (£1000 PD) CdCl2, as well as 0.476 mM (PD) and 746 mM (£1000 PD)
K2Cr2O7. At day 14, when all organ systems were completely developed, the embryos were terminated and the effect of these metals
on liver tissue and cellular morphology was determined with light- and transmission electron microscopy (TEM). The intracellular
localization of these metals was determined using electron energy-loss spectroscopy (EELS). With light microscopy, the PD of both
Cd and Cr had no effect on liver tissue or cellular morphology. At £1000 PD both Cd and Cr caused sinusoid dilation and tissue
necrosis. With TEM analysis, Cd exposed hepatocytes presented with irregular chromatin condensation, ruptured cellular
membranes and damaged or absent organelles. In contrast Cr caused only slight mitochondrial damage. EELS revealed the bioaccumulation
of Cd and Cr along the cristae of the mitochondria and chromatin of the nuclei.
