Increased incidence of intranuclear rods and unusual cytoplasmic inclusions in clarke neurons in rats subjected to neonatal peripheral nerve injury: an ectron microscopic study

ABSTRACT

Clarke's nucleus of young adult rats whose right sciatic nerves were crushed in the first postnatal day was examined with the electron microscope and the ultrastructure of Clarke neurons was described on both the control [left] and experimental [right] ides. The general fine tructure of Clarke cells appeared quite similar to that of other neurons. Unlike other neurons. Clarke cells showed an eccentric nucleus and Nissl substance characterized by parallel cisternae of rough endoplasmic reticulum. Three types of intranuclear rods and two distinctive cytoplasmic inclusions, termed fibrillary inclusion bodies and nematosomes, have been identified in Clarke neurons on the experimental side. The nuclear rods consisted of microfilaments or microtubules and were called tubular, filamentous and filamentous.crystalloid rods. The fibrillary inclusion bodies appeared as balls of densely packed neurofilaments enveloped by a multiloculated membrane. The nematosomes consisted of a reticular network of filamentous strands, lacked a limiting membrane and were always present in ribosome-rich areas. On the control side, the cytoplasmic inclusion bodies were not seen, while the intranuclear rods were observed only in two clarke cells. Mother distinctive feature of Clarke cells on the experimental side was the presence of peculiar dendritie profiles packed with mitochondria and glyeogen particles