Microvascular system of the lumbar dorsal root ganglia in rats. Part I: a 3D analysis with scanning electron microscopy of vascular corrosion casts.
OBJECTIVE
So far, the morphological features of the vascular system supplying the dorsal root ganglion (DRG) have been inferred only from microangiograms. However, in the past most of these studies lacked 3D observations. This study presents the details of the microvasculature of the lumbar DRG visualized by scanning electron microscopy of vascular corrosion casts.


METHODS
Wistar rats were anesthetized with intraperitoneal sodium pentobarbital. After thoracotomy, the vascular system was perfused with heparinized saline, and Mercox resin was injected into the thoracic aorta. After polymerization of the resin, the vascular casts were macerated with potassium hydroxide, washed with water, and dried. The casts were examined with a scanning electron microscope.


RESULTS
The vascular cast of the DRG was observed to have a higher density of vessels than the nerve root. Bifurcation or anastomoses of capillaries took place at approximately right angles, in a T-shaped pattern. Within the DRG, both the arterial supply and the capillary network contained blood flow control structures (ring-shaped constrictions in the cast probably representing a vascular sphincter in the microvessel). Three types of vessels could be distinguished: tortuous, straight, and bead-like capillaries. The dilations, bulges, and tortuousness of capillaries could serve the function of locally increasing the capillary surface area in a sensory neuron.


CONCLUSIONS
The results of this study suggest a causal relationship between the metabolic demands of local neuronal activity and both the density of the capillary network and the placement of the blood flow control structures.
Kobayashi
Shigeru
S
Department of Orthopaedics and Rehabilitation Medicine, Faculty of Medical Sciences, The University of Fukui, Matsuoka, Fukui, Japan. kshigeru@u-fukui.ac.jp
Mwaka
Erisa Sabakaki
ES
Baba
Hisatoshi
H
Takeno
Kenichi
K
Miyazaki
Tsuyoshi
T
Matsuo
Hideaki
H
Uchida
Kenzo
K
Meir
Adam
A
D000818:Animals; D002196:Capillaries / Q000648:ultrastructure; D016319:Corrosion Casting; D005727:Ganglia, Spinal / Q000098:blood supply* / Q000648:ultrastructure*; D021621:Imaging, Three-Dimensional / Q000379:methods; D008159:Lumbar Vertebrae; D008855:Microscopy, Electron, Scanning / Q000379:methods; D055806:Microvessels / Q000648:ultrastructure*; D051381:Rats; D017208:Rats, Wistar; D013126:Spinal Nerve Roots / Q000098:blood supply / Q000648:ultrastructure