The schematic presentation of intrathecal catheter placement.

<p>A–C7 –Th1 level of spinal cord, B–intrathecal catheter, C–a place of surgery.</p

Electron micrographs of severe demyelination in the area of the fasciculus gracilis of the dorsal column in the rat treated with the intrathecal infusion of 10 nmol/min of kynurenic acid (KYNA) per 5 days.

<p>A–in the area of severe demyelination, most of axons are naked, there are 3 astrocytes (As), one oligodendrocyte (OL) and a small blood vessel (bv). B–on higher magnification, the oligodendrocyte appears to have a compact cytoplasm devoid of processes; it is surrounded by many naked axons, some of the diameter greater than 2 μM (asterices) and a few myelinated axons. Size bars; A– 10 μM, B– 2 μM.</p

Electron micrographs of damaged myelin sheaths from the spinal cord of rats infused intrathecally with kynurenic acid (KYNA) for 7 days.

<p>A–an area from the dorsal column of a rat infused with 0.01 nmol/min of KYNA with an astrocyte (As) and an oligodendrocyte (OL) surrounded by damaged myelin sheaths. B–in this detail of A delineated by the white box, a segment of well compacted thick myelin sheath (Ms) passes into a segment were all lamellae are widely separated due to disintegration of compaction at the intraperiod line indicated by arrows. C–an example of a damaged myelin sheath from a single axon (Ax) from the lateral column of the rat infused with 10 nmol/min KYNA were a few well compacted lamellae (white double headed arrows) are widely separated by uncompacted lamellae (black arrows). D–in the lateral column of a rat infused with 1 nmol/min of KYNA, an axon (Ax) has a damaged myelin with segmental loss of compaction due to separation of lamellae at the intraperiod line (white arrow). There is a well-compacted thick myelin sheath (Ms) in the adjacent axon. E–lateral column from a rat infused with 0.0002 pmol/min of KYNA per 7 days, with multiple myelin sheaths showing the segmental loss of compaction and one oligodendrocyte (OL). The box indicates the area displayed in higher magnification in F–with two axons (Ax) surrounded by uncompacted myelin lamellae. Size bars; A, E– 5 μM, B, C, D– 100 nM, F– 1 μM.</p

Histomicrographs of the sections of the cervical spinal cord of rats infused intrathecally with kynurenic acid (KYNA).

<p>Toluidine blue (TB) stain. In the dorsal–A, and lateral–B, columns from a rat treated with 0.0002 pmol/min of KYNA per 7 days, there are sparse, individual axons with thickened myelin sheaths staining dark with TB. In the dorsal column–C of a rat infused with 0.01 nmol/min of KYNA per 7 days there are scattered myelin sheaths that are thickened, whereas in the lateral column–D, in the sub-pial areas, there are greater numbers of thickened myelin sheaths and there are also large axons that have dilated and attenuated myelin sheaths (arrows). The numbers of abnormal myelin sheaths appear to increase in the fasciculus gracilis (delineated by the arrow heads) and in the subpial areas of the dorsal and of the lateral and ventral columns in rats infused with; 0.1 nmol/min of KYNA per 7 days, E–dorsal column, F–lateral column; 1 nmol/min of KYNA per 7 days, G–dorsal column, H–ventral column; and 10 nmol/min of KYNA infused per 5 days, I–dorsal column, J–lateral column. Size bars– 50 μM.</p