Visualization of Protein Aggregation in Nerve Cells After Ischemia/Reperfusion by Ubiquitin Immunohistochemistry and Impregnative Nauta Method

Using ubiquitin immunohistochemistry and impregnative Nauta method we demonstrated that ubiquitin positivity and Nauta positivity in the neurons affected with ischemic injury in the lumbosacral spinal cord of rabbits and dogs may be of the same origin. Increased number of ubiquitin-positive aggregates was found in the cytoplasm of neurons in the intermediate zone and lamina IX of ventral horns of spinal cord in rabbits after 30 min of ischemia followed by 24 h lasting reperfusion. Nauta-positive, flocculent, intracytoplasmic, dark clusters appeared in the same localization in the canine lumbosacral spinal cord neurons after 30 min of ischemia and 24 h of reperfusion. Ubiquitin aggregates and Nauta-positive dark clusters in the injured spinal cord neurons could be the first light microscopic signs of slow neuronal death following spinal cord ischemia and reperfusion.

Centrifugal fibres in the avian visual system

A study has been made of the origin and course of the centrifugal fibres in the visual pathway of the pigeon using the Nauta method. Lesions in the mid-brain involving the isthmo-optic nucleus result in fibre degeneration which can be traced through the isthmo-optic tract to the chiasma and thence into the contralateral optic nerve and retina. In the retin a severe degeneration is found throughout the optic nerve layer, and occasional degenerating fibres can be traced through the ganglion cell layer to the inner aspect of the bipolar cell layer. Here they terminate in endings similar to those described by Cajal (1889) and Dogiel (1895) in relation to amacrine cells. The projection to the retina is completely crossed. Counts of the number of cells in the isthmo-optic nucleus indicate that the number of centrifugal fibres is approximately 10000; they form 1 % of the total number of fibres in the optic nerve. The isthmo-optic nucleus receives afferents from the tectum, and in this projection there would appear to be a well-defined organization.