| Description |
The substantia nigra of homozygous recessive, hyperbi1irubinemic Gunn rats, three days to six months old, were studied using the electron microscope. The brains were perfused carefully with a ]Z formaldehyde-]% gluteraldehyde solution In a 0.12 molar phosphate buffer, and post-fixed in 2% osmium tetroxide. In 1-2 week old animals, the cytoplasm of neuronal cell bodies and dendrites appears disrupted by loosely arranged, irregularly shaped, concentric membranous whorls. Mitochondria also are distended with osmophillc granules measuring 200-300 Å in diameter. Scattered granules are located within the mitochondrial matrix. Larger collections of these granules cause the cristae to become remarkably distended and, consequently, the mitochondrial profiles are enlarged. In 3~12 week old animals, the membranous whorls are more o compact and regularly shaped, and exhibit a periodicity of 40-60 Å These whorls appear to cause less cytoplasmic disruption. They are limited to a smaller portion of the soma and are usually located In the periphery. Fewer examples of intramitochondrial granules are found in these older animals. However, segments of cisternae of rough endoplasmic reticulum become engorged with dense granules. These are larger, 400-600 Å, than those encountered in mitochondria. The endo-plasmic collections of granules appear to result from the coalescing of smaller granules. The axons and axon terminals in the animals studied do not appear to be structurally modified. The major effect of the enxyme deficiency disorder on the glia is the cytoplasmic accumulation of lipid material in astrocytes. |
