Autometallographic mapping of mercury deposits in the spinal cord of rats treated with inorganic mercury.

The autometallographic method has been used in conjunction light and electron microscopy to determine the exact localization of mercury in the rat spinal cord. Adult male Wistar rats were treated intraperitoneally with accumulative doses of mercuric chloride (100-200 micrograms HgCl2 daily). Transverse sections of the first cervical segment (C1), fifth cervical segment (C5), sixth thoracic segment (T6), and first lumbar segment (L1) of the spinal cord were examined. The distribution pattern of mercury was dose dependent. In ventral horn motoneurons and neurons of nucleus dorso-medialis (C1) pronounced staining was found after a total dosage of 1200 micrograms HgCl2. In nucleus intermedio-lateralis (T6, L1) and nucleus cervicalis centralis (C1) stained neurons were first seen after 2600 micrograms HgCl2. Ultrastructurally, mercury deposits were exclusively located in lysosomes of neurons, astrocytes, endothelial cells, and ependymal cells.