THE SMALL INTESTINAL ENTEROCYTES OF RATS DURING LEAD-POISONING - THE APPLICATION OF THE TIMM SULFIDE SILVER METHOD AND AN ULTRASTRUCTURAL-STUDY

Young male rats were divided into 3 groups which received approximately 100 mg of a lead acetate/kg b.w. per day in their drinking water during 2, 30 and 60 d, respectively. Samples from the jejunum were processed for transmission electron microscopy (TEM), and after 60 d of exposure blocks of tissue were also processed to evaluating the Timm sulphide silver reaction sites in the epithelial absorptive cells in TEM according to DANCHER and ZIMMER (5). The ultrastructure of enterocytes in poisoned rats at 2 days was similar to the controls. A marked feature of about one third of the rat enterocytes exposed to lead for 30 d was the presence of numerous, small rough-membraned vesicles and prominent, dilated Golgi complexes in their cytoplasm. Most of the enterocytes at the 60th d of lead-exposed rats had a vacuolated cytoplasm associated with the prominent Golgi complexes and vacuoles of various size. They also had pleomorphic rough-membraned vesicles and dilated cisternae of the RER. The presence of the Timm reaction deposits has been observed on the microvillar surface of the brush border in connection with the enterocyte plasma membrane, and in the extracellular space between epithelial cells. Furthermore, Timm precipitates were found in extravascular spaces surrounding capillaries, between endothelial cells, and in the capillary lumen.