The effects of lead nitrate on the central nervous system of the chick embryo I. Observations of light and electron microscopy.

The effects of lead on the developing central nervous system were studied for the first time by light and electron microscopy in the chick embryo after injecting lead nitrate into the air space of the egg at 10 days of incubation. Lead-treated embryos showed curled toes as a sign of neurological injury, weighed less and were smaller in size than controls of the same incubation age. Light microscope studies of brain and spinal cord revealed the presence of numerous accumulations of blood cells which appeared to accompany the extensive injury found in those tissues. Ultrastructure of spinal cord suggests that neuroglial astrocytes in the vicinity of blood vessels are altered in leaded embryos. Prominent morphological changes were extensive vacuolation and disorganization of the endoplasmic reticulum of the cell. The evidence indicates that the spinal cord like the developing brain is subject to the biological effects of lead. The results encourage further experimentation using the chick embryo for studies of lead neuropathies.