Dorsal root ganglion microvasculature in the common tree shrew (Tupaia glis) as revealed by SEM of plastic corrosion cast

Abstract

The microvasculature of the dorsal root ganglion (DRG) has been studied in 15 adult common tree shrews of both sexes weighing between 120-180 g. The animals are divided into 2 groups. The first group is used for the study of DRG with light and transmission electron microscopy. The second group is used for the study of the vascular casts of DRG in conjunction with SEM. It is found that the common tree shrew DRG contains the clusters of cell bodies of neurons locating in the peripheral region while the nerve fibers pass through the central region. Each ganglionic neuron with concentric nucleus is surrounded by satellite cells. It is noted that there are more blood vessels in the area where the neurons are predominated than in the area occupied by nerve fibers. The DRG are supplied by the branches of radicular arteries. The radicular arteries arise from the vertebral, posterior intercostal and lumbar arteries. The radicular artery passes through the intervertebral foramen and gives off branches to supply the DRG by forming intraganglionic capillary network. Some of the radicular arteries proceed to the spinal cord by becoming either an anterior or posterior radicular artery and occasionally divide to form both anterior and posterior radicular arteries. The anterior and posterior radicular arteries become the anterior and posterior spinal artery, respectively. In addition, the DRG receives the blood from small branches of the radicular artery supplying the proximal portion of the spinal nerve and nerve root to form subcapsular capillary network and intraganglionic capillary network. The arteries supplying the spinal nerve and the nerve root are also the branches of segmental artery. All capillary networks drain the blood into the venous plexus around the DRG which connects with the internal vertebral venous plexus and segmental vein. Neither fenestration in the wall of capillaries nor evidence of portal-like circulation in the DRG is observed.