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Correlation with superior cervical sympathetic ganglion and sympathetic nerve innervation of intracranial artery-electron microscopical studies
Brain Research, 1.88 (1980) 3341 © Elsevier/North-Holland Biomedical Press
33
CORRELATION WITH SUPERIOR CERVICAL SYMPATHETIC G A N G L I O N AND SYMPATHETIC NERVE INNERVATION OF I N T R A C R A N I A L A R T E R Y - E L E C T R O N MICROSCOPICAL STUDIES
T O M O H I K O SA~IO, SO SATO and JIRO S U Z U K I
Division of Neurosurgery, Institute of Brain Diseases, Tohoku University School of Medicine, Sendai and (S.S.) Department of Neurosurgery, Saiseikan Hospital, Yamagata (Japan) (Accepted June 9th, 1979)
Key words: sympathetic nerve innervation - - cervical sympathetic ganglion - - sympathetic denervation - - adrenergic small cored vesicle
SUMMARY
When the superior cervical ganglion was resected in dogs, nerve degeneration in arterial walls began after about 28 h and marked degenerative substance was shown after 40-48 h; after 4 days the small cored vesicles of adrenergic axons disappeared. The same condition was seen after 3 months, but after 6 months the small cored vesicles were again visible. When the middle cerebral artery was examined by separating it into the perforating artery near to the internal carotid artery and the peripheral portion of the middle cerebral artery, degeneration of the nerve fibers of the arterial walls occurred earlier in the more proximal portion. The distribution of adrenergic nerve fibers from the superior cervical ganglion is bilateral in the anterior cerebral artery from the anterior communicating artery to the peripheral region, basilar artery, and vertebral artery, but ipsilateral only in the anterior cerebral artery as far as the anterior communicating artery, middle cerebral artery, posterior communicating artery, posterior cerebral artery and superior cerebellar artery. Degeneration of nerve fibers of the walls of these cerebral arteries was not seen ever after stellate ganglionectomy in both sides.
INTRODUCTION
Recently, using electron microscopic and fluorescent histological methods, the location of nerve terminals has been elucidated2,S,9,t1,la,16,1v; the majority have been found to be adrenergic fibers and a portion to be cholinergic fibers4,7,11,13. With regard to the source of these nerve fibers, particularly the sympathetic ones, other than the superior cervical ganglion, the middle cervical and stellate ganglia and upper
34 cervical nerves are all involved1,6,15, and there are also central noradrenergic fibers innervating arterioles within the brain parenchymaZ, 4. In the current study, we have examined the distribution of vasomotor nerves in cerebral arterial walls by an electron microscope and, further, have investigated their origins. By removing the superior cervical ganglion or the stellate ganglion in animals, pathological changes in the vasomotor nerves of various cerebral trunk arteries were elucidated both in terms of their spatial location and their progress in time. MATERIALS AND METHODS For the superior cervical ganglionectomy experiments, 39 adult mongrel dogs weighing 7-12 kg were used. Under Nembutal anesthesia, bilateral superior cervical ganglionectomy and unilateral superior cervical ganglionectomy were performed in 11 and 28 dogs, respectively. The cerebral vessels were excised and immediately fixed 6, 12, 24, 28, 40, 45 and 48 h, 4, 7, and 30 days and 2, 3 and 6 months after the removal of the superior cervical ganglion.
Fig. 1. Glutaraldehyde-osmium tetroxide fixation. Degeneration was not seen 11 h after bilateral superior cervical ganglionectomy in the middle cerebral artery of dogs. Axons (A1) containing small cored vesicles and axons (Az) containing small clear vesicles and large cored vesicles can be seen. Glycogen granules (G) are also visible in a portion of the axon. Sin, smooth muscle cells. M, mitochondria. Calibration: 1 /iM.
35
Fig. 2. Middle cerebral artery of the dog after glutaraldehyde-osmium tetroxide fixation, a: vacuotation (V) seen in the axons 28 h following bilateral superior cervical ganglionectomy, b: after 40 h, considerable degenerated material (D) could be seen. c ."after 4 days, small cored vesicles could not be observed anywhere. Sin, smooth muscle cells. Calibration : 1 /~M.
36
Fig. 3. Middle cerebral artery of the dog after potassium permanganate fixation. Three months following unilateral superior cervical ganglionectomy, only small clear vesicles (A2) are present. F, fibroblast. Calibration: 1 /~M.
In the stellate ganglionectomy experiments, 14 adult mongrel dogs weighing 7-10 kg were used. Bilateral and unilateral stellate ganglionectomies were performed in 6 and 8 dogs, respectively. The cerebral vessels were excised and fixed 2, 7 or 14 days after the removal of the stellate ganglion. Fixed materials included the anterior cerebral, anterior communicating, middle cerebral, posterior cerebral, posterior communicating, superior cerebral, basilar and vertebral arteries. Fixation was accomplished by placing the arteries in a phosphate buffer solution (pH 7.4) with 2 ~ glutaraldehyde at room temperature for 30 min, followed by a second fixation by placing them for 2 h in cold (4 °C) 1.0 ~ osmium tetroxide-phosphate buffer solution (pH 7.4). Fixation was also done with 3 ~ potassium permanganate in veronal buffer (pH 7.3) at 4 °C for 2 h. After fixation, ethanol dehydration was performed and, following propiren oxide treatment, they were embedded in Epon 812. Samples to be studied microscopically were dyed with toluidine blue and those to be studied electron microscopically were dyed with both uranyl acetate and alkaline lead. These samples were observed under a Hitachi JEM-T7S electron microscope.
37
Fig. 4. Middle cerebral artery of the dog after potassium permanganate fixation. Small cored vesicles (A1) seen after 6 months. F, fibroblast. Calibration: ! /~M.
RESULTS
Degeneration process of the nerves in cerebral arterial walls after superior cervical ganglionectomy No change could be seen in any nerve fibers between 6 and 24 h following superior cervical ganglionectomy (Fig. 1). After 28 h, the axons were vacuolated and a small number of dense bodies appeared, but the small cored vesicles could still be easily identified. After 40-48 h, the nerve terminals in the arterial walls became darkened and degenerative substances could be clearly seen; axoplasm was destroyed and mitochondria could not be seen. During this time, small cored vesicles disappeared and none could be found in the middle cerebral artery near the internal carotid artery, in the anterior cerebral artery, posterior cerebral artery, or the basilar artery. On the other hand, they were still present in the middle cerebral artery, the peripheral portions of the anterior cerebral artery and the basilar artery near the vertebral artery. However, after the fourth day none of these small cored vesicles could be seen anywhere (Fig. 2), and this situation remained the same for three months (Fig. 3). After 6 months, however, some axons with these small cored vesicles could once again be seen (Fig. 4).
38
MAPS OF ULTRASTRUCTURAL CHANGES OF THE CEREBRAL NERVI VASORUM AFTER SUPERIQR CERVICAL GANGLI@NECTOMY
1
BILATERAL SUP, CERVICAL GANGLIOIIECTOr~Y
UNILATERAL SUP, CERVICAL GANGLIONECTOMY 0 0 Z~
DEGENERATED NERVE FIBERS NON-DEGENERATED NERVE FIBERS COMBINED: WITH ArID WITHOUT DEGENERATED NERVE FIBEPS
Fig. 5. Schema of the degeneration of cerebral arterial nerve fibers following superior cervical ganglionectomyin the dog. • degenerated nerve fibers. ,.~ non-degeneratednerve fibers, fL degenerated and non-degenerated nerve fibers mixed together.
Local and time differences in degeneration of the nerve By comparing the degeneration over time of the middle cerebral artery near the internal carotid artery and the perforating arteries with the peripheral portion of the middle cerebral artery, at 40 h after the removal of the superior cervical ganglion, markedly degenerative substances were found and no small cored vesicle was noted in the middle cerebral artery near to the internal carotid artery as well as in the perforating artery of 200/~m in diameter, whereas degenerative substances and small cored vesicles were found to coexist in the nerve of the cerebral arterial wall existing in the gyrus precentralis with approximately 200 #m diameter at the point 5.4 cm apart from the branch of the internal carotid artery toward the peripheral direction. Distribution of degenerated nerves in the walls o f various cerebral arteries after unilateral or bilateral superior cervical ganglionectomy In the case of unilateral ganglionectomy, degeneration of adrenergic nerve fibers of the arterial walls was seen on the same side as the ganglionectomy in the anterior
39 cerebral artery as far as the anterior communicating artery, the middle cerebral artery, the posterior communicating artery, the posterior cerebral artery and the superior cerebellar artery, but not in these arteries contralateral to the ganglionectomy. Furthermore, both degenerated and intact nerve fibers were found in the anterior cerebral artery from the anterior communicating artery to the peripheral region, the basilar artery, and the vertebral artery. Particularly in the anterior communicating artery and the basilar artery, the distribution of degenerated nerve fibers as seen through serial sections showed that degenerated and undegenerated fibers were mixed together, rather than being separated on the left or right side only. In the bilateral superior cervical ganglionectomy animals, degeneration of adrenergic fibers was seen in all the arterial walls of the anterior communicating, basilar and vertebral arteries (Fig. 5).
Nerve degeneration in various cerebral arterial walls after stellate ganglionectomy No degenerative substance appeared in and any small cored vesicles did not disappear from any vessels of the circle of Willis, the basilar and the vertebral arteries after the resection of the stellate ganglion, either at one side or both sides. DISCUSSION Since the introduction of electron microscopical techniques, the ultrastructure of nerve terminals in cerebral vessels has been greatly elucidated~,lo-13,x6, is, and the adrenergic fibers have also been investigatedS,8,13A 4 with a fluorescent histochemical method in cats, guinea pigs, rabbits and rhesus monkeys. According to those reports, the distribution of fluorescent fibers is particularly rich in the internal carotid artery, the posterior communicating artery and the anterior cerebral artery, followed by the middle cerebral artery, with fewer in the basilar artery, and still fewer in the vertebral artery, superior cerebellar artery, inferior cerebellar artery and posterior cerebral artery. With regard to the arteries in the brain, the arterioles as well as the perforating artery running to the choroid plexus, anterior hypothalamus, subthalamus and central tegmentum are also reported to show dense fluorescence. Our electron microscopic observation disclosed that the small cored vesicles exist to the same degree of density in the internal carotid artery, the middle cerebral artery, the posterior communicating artery and the basilar artery. The anterior cerebral artery shows small cored vesicles in plenty up to the azygos artery where the right and left anterior cerebral arteries are united into one artery, but the small cored vesicles become significantly less in its peripheral part. The perforating artery running into the hypothalamus and the thalamus was found to be abundant in small cored vesicles even in the arterioles of 100 #m outside diameter as was recognized by the fluorescent method. This seems to indicate that the pertaining area is strongly innervated. In animals in which superior cervical ganglionectomy was performed, some differences with time were seen in both the observations with fluorescent staining and observations with the electron microscope. Using the fluorescent method, no changes in the nerves of cerebral arterial walls were seen 18-24 h following ganglionectomy,
40 but after 32 h fluorescent fibers began to disappear and after 48 h almost no fluorescence was visible 7,9. On the other hand, using the electron microscope, degenerated substance could be seen between 18 and 32 h and the disappearance of small cored vesicles after 48 h was confirmed. In our experiments in dogs, no changes in nerve fibers were seen between 6 and 24 h, but vacuoles appeared after 28 h and, between 40 and 48 h, markedly degenerated substances were observed. Although it is said that small cored vesicles disappear after 48 h, this is not found in all vessels, but rather there are local differences. Specifically, small cored vesicles could be observed anywhere on each main artery near the internal carotid artery or perforating arteries after 40 h, whereas they were still visible in the area of the peripheral portion of the middle cerebral artery. Consequently, the process of degeneration is thought to occur earlier nearer to the proximal portion of the internal carotid artery and soon thereafter proceeds to more distal areas. Concerning the origin of the cerebrovascular nerves, the vast majority of the adrenergic fibers are said to originate from the superior cervical ganglion and partly from the middle cervical sympathetic ganglion and the stellate ganglion1,6,10,15. This hypothesis, however, is not always confirmed by researchers. Nielsenl2, la and Peerless et al. 14,15 have observed the cerebral vessels of rats, rabbits and cats using fluorescent techniques and found that, in unilaterally superior cervical ganglionectomized animals, fluorescence disappears in the internal carotid and middle cerebral arteries, and, in animals with bilateral superior cervical ganglionectomy, fluorescence cannot be seen in the anterior cerebral artery, posterior cerebral artery and the basilar artery, whereas almost no influence at all was seen on the above vessels following stellate ganglionectomy. Researchers are almost in agreement with one another as far as the innervation system by the internal carotid artery, the middle cerebral artery and the anterior cerebral artery is concerned, but do not reach a conclusion when it comes to the innervation system by the vertebral and basilar arteries, maybe because of the different species of animals used in their experiments. In our experiments on dogs, degeneration of adrenergic nerve fibers following unilateral superior cervical ganglionectomy was not complete, but was complete after bilateral ganglionectomy. Adrenergic nerve fibers on the side of unilateral superior cervical ganglionectomy showed complete degeneration in the posterior communicating artery, but no changes were seen following stellate ganglionectomy, which suggests that the majority of the nerves to the area of the basilar artery reach the basilar artery via the internal carotid and posterior communicating artery.
REFERENCES 1 Christensen, K., Polley, E. H. and Lewis, E., The nerves along the vertebral artery and innervation of the blood vessels of the hindbrain of the cat, J. comp. Neurol., 96 0952) 71-91. 2 DaM, E. and Nelson, E., Electron microscopic observations of human intracranial arteries, II. Innervation, Arch. Neurol. (Chic.), 10 (1964) 158-164. 3 Edvinsson, L., Lindvall, M., Nielsen, K. C. and Owman, Ch., Are brain vessels innervated also by central (non-sympathetic) adrenergic neurones? Brain Research, 63 (1973) 496-499.
41 4 Hartman, B. K., et al., The use of dopamine fl-hydroxylase as a maker for the central noradrenergic nervous system in the rat brain, Proe. nat. Acad. Sei. (Wash.), 69 (1972) 2722-2726. 5 Hern~indez-P6rez, M. J. and Stone, H. J., Sympathetic innervation of the circle of Willis in the macaque monkey, Brain Research, 80 (1974) 507-511. 6 Hoffman, H. H. and Kuntz, A., Vertebral nerve and plexus, A.M.A. Arch. Surg., 74 (1957) 430437. 7 Iwayama, T., Furness, J. B. and Burnstock, G., Dural adrenergic and cholinergic innervation of the cerebral arteries of the rat. An ultrastructural study, Cireulat Res., 26 (1970) 635-646. 8 Kajikawa, H., Mode of the sympathetic innervation of the cerebral vessels demonstrated by the fluorescent histochemical technique in rats and cats, Arch. Jap. Chir., 38 (1969) 227-235. 9 Kajikawa, H., et al., Studies on adrenergic innervation of the cerebral vessels using a histochemical fluorescent method, Hiroshima, J. Med. Sci., 22 (1973) 169-180. 10 Nelson, E. and Rennels, M., Innervation of intracranial arteries, Brain, 93 (1970) 475-490. 11 Nelson, E. and Rennels, M., Neuromuscular contacts in intracranial arteries of the cat, Science, 167 (1970) 301-302. 12 Nielsen, K. C. and Owman, Ch., Adrenergic innervation of pial arteries related to the circle of Willis in the cat, Brain Research, 6 (1967) 773-776. 13 Nielsen K. C., Owman, Ch. and Sporrong, B., Ultrastructure of the autonomic innervation apparatus in the main pial arteries of rats and cats, Brain Research, 27 (1971) 25-32. 14 Peerless, S. J. and Yasargil, M. G., Adrenergic innervation of the cerebral blood vessels in the rabbit, J. Neurosurg., 35 (1971) 148-154. 15 Peerless, S. J. and Kendall, M. J., Subarachnoid Hemorrhage and Cerebrovascular Spasm., Thomas, Springfield, Ill., 1975, pp. 38-54. 16 Samarasinghe, D. D., The innervation of the cerebral arteries in the rat. An electron microscopic study, J. Anat. (Lond.), 99 (1965) 815-828. 17 Sato, S., An electron microscopic study on the innervation of the intracranial artery of the rat, Amer. J. Anat., 118 (1966) 873-890. 18 Sato, S. and Suzuki, J., Anatomical mapping of the cerebral nervi vasorum in the human brain, J. Neurosurg., 43 (1975) 559-568.
33
CORRELATION WITH SUPERIOR CERVICAL SYMPATHETIC G A N G L I O N AND SYMPATHETIC NERVE INNERVATION OF I N T R A C R A N I A L A R T E R Y - E L E C T R O N MICROSCOPICAL STUDIES
T O M O H I K O SA~IO, SO SATO and JIRO S U Z U K I
Division of Neurosurgery, Institute of Brain Diseases, Tohoku University School of Medicine, Sendai and (S.S.) Department of Neurosurgery, Saiseikan Hospital, Yamagata (Japan) (Accepted June 9th, 1979)
Key words: sympathetic nerve innervation - - cervical sympathetic ganglion - - sympathetic denervation - - adrenergic small cored vesicle
SUMMARY
When the superior cervical ganglion was resected in dogs, nerve degeneration in arterial walls began after about 28 h and marked degenerative substance was shown after 40-48 h; after 4 days the small cored vesicles of adrenergic axons disappeared. The same condition was seen after 3 months, but after 6 months the small cored vesicles were again visible. When the middle cerebral artery was examined by separating it into the perforating artery near to the internal carotid artery and the peripheral portion of the middle cerebral artery, degeneration of the nerve fibers of the arterial walls occurred earlier in the more proximal portion. The distribution of adrenergic nerve fibers from the superior cervical ganglion is bilateral in the anterior cerebral artery from the anterior communicating artery to the peripheral region, basilar artery, and vertebral artery, but ipsilateral only in the anterior cerebral artery as far as the anterior communicating artery, middle cerebral artery, posterior communicating artery, posterior cerebral artery and superior cerebellar artery. Degeneration of nerve fibers of the walls of these cerebral arteries was not seen ever after stellate ganglionectomy in both sides.
INTRODUCTION
Recently, using electron microscopic and fluorescent histological methods, the location of nerve terminals has been elucidated2,S,9,t1,la,16,1v; the majority have been found to be adrenergic fibers and a portion to be cholinergic fibers4,7,11,13. With regard to the source of these nerve fibers, particularly the sympathetic ones, other than the superior cervical ganglion, the middle cervical and stellate ganglia and upper
34 cervical nerves are all involved1,6,15, and there are also central noradrenergic fibers innervating arterioles within the brain parenchymaZ, 4. In the current study, we have examined the distribution of vasomotor nerves in cerebral arterial walls by an electron microscope and, further, have investigated their origins. By removing the superior cervical ganglion or the stellate ganglion in animals, pathological changes in the vasomotor nerves of various cerebral trunk arteries were elucidated both in terms of their spatial location and their progress in time. MATERIALS AND METHODS For the superior cervical ganglionectomy experiments, 39 adult mongrel dogs weighing 7-12 kg were used. Under Nembutal anesthesia, bilateral superior cervical ganglionectomy and unilateral superior cervical ganglionectomy were performed in 11 and 28 dogs, respectively. The cerebral vessels were excised and immediately fixed 6, 12, 24, 28, 40, 45 and 48 h, 4, 7, and 30 days and 2, 3 and 6 months after the removal of the superior cervical ganglion.
Fig. 1. Glutaraldehyde-osmium tetroxide fixation. Degeneration was not seen 11 h after bilateral superior cervical ganglionectomy in the middle cerebral artery of dogs. Axons (A1) containing small cored vesicles and axons (Az) containing small clear vesicles and large cored vesicles can be seen. Glycogen granules (G) are also visible in a portion of the axon. Sin, smooth muscle cells. M, mitochondria. Calibration: 1 /iM.
35
Fig. 2. Middle cerebral artery of the dog after glutaraldehyde-osmium tetroxide fixation, a: vacuotation (V) seen in the axons 28 h following bilateral superior cervical ganglionectomy, b: after 40 h, considerable degenerated material (D) could be seen. c ."after 4 days, small cored vesicles could not be observed anywhere. Sin, smooth muscle cells. Calibration : 1 /~M.
36
Fig. 3. Middle cerebral artery of the dog after potassium permanganate fixation. Three months following unilateral superior cervical ganglionectomy, only small clear vesicles (A2) are present. F, fibroblast. Calibration: 1 /~M.
In the stellate ganglionectomy experiments, 14 adult mongrel dogs weighing 7-10 kg were used. Bilateral and unilateral stellate ganglionectomies were performed in 6 and 8 dogs, respectively. The cerebral vessels were excised and fixed 2, 7 or 14 days after the removal of the stellate ganglion. Fixed materials included the anterior cerebral, anterior communicating, middle cerebral, posterior cerebral, posterior communicating, superior cerebral, basilar and vertebral arteries. Fixation was accomplished by placing the arteries in a phosphate buffer solution (pH 7.4) with 2 ~ glutaraldehyde at room temperature for 30 min, followed by a second fixation by placing them for 2 h in cold (4 °C) 1.0 ~ osmium tetroxide-phosphate buffer solution (pH 7.4). Fixation was also done with 3 ~ potassium permanganate in veronal buffer (pH 7.3) at 4 °C for 2 h. After fixation, ethanol dehydration was performed and, following propiren oxide treatment, they were embedded in Epon 812. Samples to be studied microscopically were dyed with toluidine blue and those to be studied electron microscopically were dyed with both uranyl acetate and alkaline lead. These samples were observed under a Hitachi JEM-T7S electron microscope.
37
Fig. 4. Middle cerebral artery of the dog after potassium permanganate fixation. Small cored vesicles (A1) seen after 6 months. F, fibroblast. Calibration: ! /~M.
RESULTS
Degeneration process of the nerves in cerebral arterial walls after superior cervical ganglionectomy No change could be seen in any nerve fibers between 6 and 24 h following superior cervical ganglionectomy (Fig. 1). After 28 h, the axons were vacuolated and a small number of dense bodies appeared, but the small cored vesicles could still be easily identified. After 40-48 h, the nerve terminals in the arterial walls became darkened and degenerative substances could be clearly seen; axoplasm was destroyed and mitochondria could not be seen. During this time, small cored vesicles disappeared and none could be found in the middle cerebral artery near the internal carotid artery, in the anterior cerebral artery, posterior cerebral artery, or the basilar artery. On the other hand, they were still present in the middle cerebral artery, the peripheral portions of the anterior cerebral artery and the basilar artery near the vertebral artery. However, after the fourth day none of these small cored vesicles could be seen anywhere (Fig. 2), and this situation remained the same for three months (Fig. 3). After 6 months, however, some axons with these small cored vesicles could once again be seen (Fig. 4).
38
MAPS OF ULTRASTRUCTURAL CHANGES OF THE CEREBRAL NERVI VASORUM AFTER SUPERIQR CERVICAL GANGLI@NECTOMY
1
BILATERAL SUP, CERVICAL GANGLIOIIECTOr~Y
UNILATERAL SUP, CERVICAL GANGLIONECTOMY 0 0 Z~
DEGENERATED NERVE FIBERS NON-DEGENERATED NERVE FIBERS COMBINED: WITH ArID WITHOUT DEGENERATED NERVE FIBEPS
Fig. 5. Schema of the degeneration of cerebral arterial nerve fibers following superior cervical ganglionectomyin the dog. • degenerated nerve fibers. ,.~ non-degeneratednerve fibers, fL degenerated and non-degenerated nerve fibers mixed together.
Local and time differences in degeneration of the nerve By comparing the degeneration over time of the middle cerebral artery near the internal carotid artery and the perforating arteries with the peripheral portion of the middle cerebral artery, at 40 h after the removal of the superior cervical ganglion, markedly degenerative substances were found and no small cored vesicle was noted in the middle cerebral artery near to the internal carotid artery as well as in the perforating artery of 200/~m in diameter, whereas degenerative substances and small cored vesicles were found to coexist in the nerve of the cerebral arterial wall existing in the gyrus precentralis with approximately 200 #m diameter at the point 5.4 cm apart from the branch of the internal carotid artery toward the peripheral direction. Distribution of degenerated nerves in the walls o f various cerebral arteries after unilateral or bilateral superior cervical ganglionectomy In the case of unilateral ganglionectomy, degeneration of adrenergic nerve fibers of the arterial walls was seen on the same side as the ganglionectomy in the anterior
39 cerebral artery as far as the anterior communicating artery, the middle cerebral artery, the posterior communicating artery, the posterior cerebral artery and the superior cerebellar artery, but not in these arteries contralateral to the ganglionectomy. Furthermore, both degenerated and intact nerve fibers were found in the anterior cerebral artery from the anterior communicating artery to the peripheral region, the basilar artery, and the vertebral artery. Particularly in the anterior communicating artery and the basilar artery, the distribution of degenerated nerve fibers as seen through serial sections showed that degenerated and undegenerated fibers were mixed together, rather than being separated on the left or right side only. In the bilateral superior cervical ganglionectomy animals, degeneration of adrenergic fibers was seen in all the arterial walls of the anterior communicating, basilar and vertebral arteries (Fig. 5).
Nerve degeneration in various cerebral arterial walls after stellate ganglionectomy No degenerative substance appeared in and any small cored vesicles did not disappear from any vessels of the circle of Willis, the basilar and the vertebral arteries after the resection of the stellate ganglion, either at one side or both sides. DISCUSSION Since the introduction of electron microscopical techniques, the ultrastructure of nerve terminals in cerebral vessels has been greatly elucidated~,lo-13,x6, is, and the adrenergic fibers have also been investigatedS,8,13A 4 with a fluorescent histochemical method in cats, guinea pigs, rabbits and rhesus monkeys. According to those reports, the distribution of fluorescent fibers is particularly rich in the internal carotid artery, the posterior communicating artery and the anterior cerebral artery, followed by the middle cerebral artery, with fewer in the basilar artery, and still fewer in the vertebral artery, superior cerebellar artery, inferior cerebellar artery and posterior cerebral artery. With regard to the arteries in the brain, the arterioles as well as the perforating artery running to the choroid plexus, anterior hypothalamus, subthalamus and central tegmentum are also reported to show dense fluorescence. Our electron microscopic observation disclosed that the small cored vesicles exist to the same degree of density in the internal carotid artery, the middle cerebral artery, the posterior communicating artery and the basilar artery. The anterior cerebral artery shows small cored vesicles in plenty up to the azygos artery where the right and left anterior cerebral arteries are united into one artery, but the small cored vesicles become significantly less in its peripheral part. The perforating artery running into the hypothalamus and the thalamus was found to be abundant in small cored vesicles even in the arterioles of 100 #m outside diameter as was recognized by the fluorescent method. This seems to indicate that the pertaining area is strongly innervated. In animals in which superior cervical ganglionectomy was performed, some differences with time were seen in both the observations with fluorescent staining and observations with the electron microscope. Using the fluorescent method, no changes in the nerves of cerebral arterial walls were seen 18-24 h following ganglionectomy,
40 but after 32 h fluorescent fibers began to disappear and after 48 h almost no fluorescence was visible 7,9. On the other hand, using the electron microscope, degenerated substance could be seen between 18 and 32 h and the disappearance of small cored vesicles after 48 h was confirmed. In our experiments in dogs, no changes in nerve fibers were seen between 6 and 24 h, but vacuoles appeared after 28 h and, between 40 and 48 h, markedly degenerated substances were observed. Although it is said that small cored vesicles disappear after 48 h, this is not found in all vessels, but rather there are local differences. Specifically, small cored vesicles could be observed anywhere on each main artery near the internal carotid artery or perforating arteries after 40 h, whereas they were still visible in the area of the peripheral portion of the middle cerebral artery. Consequently, the process of degeneration is thought to occur earlier nearer to the proximal portion of the internal carotid artery and soon thereafter proceeds to more distal areas. Concerning the origin of the cerebrovascular nerves, the vast majority of the adrenergic fibers are said to originate from the superior cervical ganglion and partly from the middle cervical sympathetic ganglion and the stellate ganglion1,6,10,15. This hypothesis, however, is not always confirmed by researchers. Nielsenl2, la and Peerless et al. 14,15 have observed the cerebral vessels of rats, rabbits and cats using fluorescent techniques and found that, in unilaterally superior cervical ganglionectomized animals, fluorescence disappears in the internal carotid and middle cerebral arteries, and, in animals with bilateral superior cervical ganglionectomy, fluorescence cannot be seen in the anterior cerebral artery, posterior cerebral artery and the basilar artery, whereas almost no influence at all was seen on the above vessels following stellate ganglionectomy. Researchers are almost in agreement with one another as far as the innervation system by the internal carotid artery, the middle cerebral artery and the anterior cerebral artery is concerned, but do not reach a conclusion when it comes to the innervation system by the vertebral and basilar arteries, maybe because of the different species of animals used in their experiments. In our experiments on dogs, degeneration of adrenergic nerve fibers following unilateral superior cervical ganglionectomy was not complete, but was complete after bilateral ganglionectomy. Adrenergic nerve fibers on the side of unilateral superior cervical ganglionectomy showed complete degeneration in the posterior communicating artery, but no changes were seen following stellate ganglionectomy, which suggests that the majority of the nerves to the area of the basilar artery reach the basilar artery via the internal carotid and posterior communicating artery.
REFERENCES 1 Christensen, K., Polley, E. H. and Lewis, E., The nerves along the vertebral artery and innervation of the blood vessels of the hindbrain of the cat, J. comp. Neurol., 96 0952) 71-91. 2 DaM, E. and Nelson, E., Electron microscopic observations of human intracranial arteries, II. Innervation, Arch. Neurol. (Chic.), 10 (1964) 158-164. 3 Edvinsson, L., Lindvall, M., Nielsen, K. C. and Owman, Ch., Are brain vessels innervated also by central (non-sympathetic) adrenergic neurones? Brain Research, 63 (1973) 496-499.
41 4 Hartman, B. K., et al., The use of dopamine fl-hydroxylase as a maker for the central noradrenergic nervous system in the rat brain, Proe. nat. Acad. Sei. (Wash.), 69 (1972) 2722-2726. 5 Hern~indez-P6rez, M. J. and Stone, H. J., Sympathetic innervation of the circle of Willis in the macaque monkey, Brain Research, 80 (1974) 507-511. 6 Hoffman, H. H. and Kuntz, A., Vertebral nerve and plexus, A.M.A. Arch. Surg., 74 (1957) 430437. 7 Iwayama, T., Furness, J. B. and Burnstock, G., Dural adrenergic and cholinergic innervation of the cerebral arteries of the rat. An ultrastructural study, Cireulat Res., 26 (1970) 635-646. 8 Kajikawa, H., Mode of the sympathetic innervation of the cerebral vessels demonstrated by the fluorescent histochemical technique in rats and cats, Arch. Jap. Chir., 38 (1969) 227-235. 9 Kajikawa, H., et al., Studies on adrenergic innervation of the cerebral vessels using a histochemical fluorescent method, Hiroshima, J. Med. Sci., 22 (1973) 169-180. 10 Nelson, E. and Rennels, M., Innervation of intracranial arteries, Brain, 93 (1970) 475-490. 11 Nelson, E. and Rennels, M., Neuromuscular contacts in intracranial arteries of the cat, Science, 167 (1970) 301-302. 12 Nielsen, K. C. and Owman, Ch., Adrenergic innervation of pial arteries related to the circle of Willis in the cat, Brain Research, 6 (1967) 773-776. 13 Nielsen K. C., Owman, Ch. and Sporrong, B., Ultrastructure of the autonomic innervation apparatus in the main pial arteries of rats and cats, Brain Research, 27 (1971) 25-32. 14 Peerless, S. J. and Yasargil, M. G., Adrenergic innervation of the cerebral blood vessels in the rabbit, J. Neurosurg., 35 (1971) 148-154. 15 Peerless, S. J. and Kendall, M. J., Subarachnoid Hemorrhage and Cerebrovascular Spasm., Thomas, Springfield, Ill., 1975, pp. 38-54. 16 Samarasinghe, D. D., The innervation of the cerebral arteries in the rat. An electron microscopic study, J. Anat. (Lond.), 99 (1965) 815-828. 17 Sato, S., An electron microscopic study on the innervation of the intracranial artery of the rat, Amer. J. Anat., 118 (1966) 873-890. 18 Sato, S. and Suzuki, J., Anatomical mapping of the cerebral nervi vasorum in the human brain, J. Neurosurg., 43 (1975) 559-568.