Rami Communicantes Research Articles

遊離組織移植による口腔顎顔面領域の機能再建に関する臨床的研究 第１報 神経付前腕皮弁の神経に血管柄を付けた場合と付けない場合の口腔知覚機能再生に関する比較検討

Althogh a considerable number of flaps for reconstruction of the oral mucosa have been reported, each of these methods is associated with disadvantages such as loss of the sensations of touch. temperature, pain, and taste, the accumulation of food, a sensation of wearing dentures, loss of the sensations of mastication, and a strange feeling in the mouth. To overcome these problems, we developed a vascularized, innervated foream flap, which is elevated without removing the ramus communicans between the radial artery and vein and the vessels that nourish the lateral cutaneous nerves. We performed reconstruction of the tongue, gingiva, and mouth floor using vascularized innervated forearm flaps (three cases) and nonvascularized innervated forearm flaps (three cases).At 6 months postoperatively, sensation recovered slightly in one of three nonvascularized innervated forearm flaps, whereas the sensations of touch, pain and temperature recovered in all three vascularized innervated forearm flaps at 2 months postoperatively.

The sensitivity of nicotinic synapses in bullfrog sympathetic ganglia to α‐bungarotoxin and neuronal‐bungarotoxin

1. The sensitivity of nicotinic synapses to alpha-bungarotoxin (alpha-Bgt) and neuronal-bungarotoxin (n-Bgt) was measured in the B and C cell systems of bullfrog paravertebral sympathetic ganglia 9 and 10 by recording extracellular compound postganglionic action potentials from the rami communicantes. 2. High concentrations (10 microM) of alpha-Bgt applied for up to 8 h had no effect upon synaptic transmission in either the B or C cell system. Ganglia pretreated with collagenase were also insensitive to alpha-Bgt. In control experiments on isolated sartorius muscle preparations, nerve-evoked twitches were fully blocked by 30-100 nM alpha-Bgt. 3. Nicotinic transmission in the B and C cell systems was reversibly blocked by 30-300 nM n-Bgt. Block appeared within 25-45 min of exposure to toxin and reversed fully with a half-time of 40-80 min. This was indistinguishable from washout times after block by 100 microM (+)-tubocurarine. 4. The results demonstrate close parallels between the bungarotoxin sensitivity of neuronal nicotinic receptors mediating ganglionic transmission in functional subclasses of bullfrog sympathetic neurones and the bungarotoxin sensitivity which has been reported for autonomic in avian and mammalian preparations.

Studies of reflexogenic effects of capsaicin and neuropeptides on neural afferents in the dog parietal pericardium

Stimulation of neural afferents in the parietal pericardium of anaesthetized, openchest dogs by local application of capsaicin (0.1–100 μg) consistently induced dose-related pressor effects and tachycardia, whereas the application (0.1–1 μg) of neuropeptides substance P (SP), neurokinin A (NKA), neurokinin B (NKB) or calcitonin gene-related peptide (CGRP) had no cardiovascular effect. Capsaicin-induced reflex responses were not affected by vagotomy, but were abolished by bilateral sectioning of the upper thoracic (T 1-T 4) white rami communicantes and stellectomy. Capsaicin-induced reflex tachycardia could also be abolished by a β-adrenoceptor blockade with propranolol (0.5 mg/kg, IV), while ganglionic blockade with pentolinium (0.5 mg/kg, IV) eliminated both the tachycardia and pressor effects. Intravenous treatment with the cyclo-oxygenase inhibitors, indomethacin (5 mg/kg) or aspirin (100 mg/kg) had no effect on reflex pressor and heart rate responses to pericardial capsaicin. Also local treatment of the pericardium with either indomethacin (1 μg/ml) or dual cyclo-oxygenase/lipoxygenase inhibitor, BW755C (10 μg/ml) failed to affect the responses to capsaicin. We conclude that (i) capsaicin-sensitive afferents which are present in the dog pericardium have a spinal origin and can initiate sympathetically-mediated reflex cardiovascular changes; (ii) the reflexogenic action of capsaicin on pericardial afferents does not depend on local production of eicosanoids; (iii) neuropeptides appear to be without reflexogenic effects on neural afferents in the dog parietal pericardium.

Lateral parascapular extrapleural approach to the upper thoracic spine

The upper thoracic vertebrae are difficult to approach surgically because of the narrowing of the thoracic inlet, the proximity of the brachial plexus, and the parascapular shoulder musculature. A novel lateral parascapular extrapleural approach to the upper thoracic vertebrae is described. The parascapular shoulder musculature (trapezius, levator scapulae, and rhomboid muscles) is reflected off the spinous processes to the scapula as a musculocutaneous flap, preserving the neurovascular supply. The paraspinal musculature is mobilized and retracted, and the upper dorsal ribs are removed with caution to avoid injury to the C-8 and T-1 nerve roots. The rami communicantes are transected, and the sympathetic chain is displaced anterolaterally. The T2-4 vertebrae can be approached unobstructed. The T-1 nerve root obstructs posterolateral access to the T-1 vertebra, necessitating an inferolateral approach underneath the T-1 nerve root axilla. Four patients with compressive myelopathy from upper thoracic vertebral metastases underwent neural decompression, vertebral reconstruction, and posterior spinal fixation with this approach. Their postoperative neurological status was either unchanged or improved. Complications included radiographic pleural effusion and superficial wound dehiscence; one patient required posterior spinal reinstrumentation for progressive kyphosis. One patient developed pneumonia 7 days postoperatively which was unresponsive to appropriate treatment. It is believed that the anatomical limitations to this region have been overcome, and that excellent exposure of the T1-4 vertebrae for neural decompression and vertebral reconstruction can be performed safely. A major advantage is that posterior spinal fixation can be carried out simultaneously.

Localization of NADPH‐diaphorase‐containing neurons in sensory ganglia of the rat

The presence of reduced nicotinamide adenine dinucleotide phosphate (NADPH)-diaphorase activity was studied histochemically in the sensory ganglia of the rat. Supraspinally, the trigeminal ganglion possessed only a few cells positively stained for NADPH-diaphorase, while a large number of positive neurons was found in the nodose ganglion. In the dorsal root ganglia, the distribution of positive cells showed a peculiar pattern in relation to spinal levels. Very minor populations (less than 2% of the total ganglionic cells) exhibited positive reaction in ganglia at levels ranging from the first cervical (C1) to fourth thoracic (T4) and from the second lumber (L2) through the entire sacral levels. In the middle to lower thoracic levels (from T5 to L1), however, abundant diaphorase-positive cells were observed. From these positive neurons it was possible to trace intensely stained nerve fibers. In the lower thoracic level, for example, dense positive fibers were seen in the ramus communicans. Retrograde tracing studies revealed that diaphorase-containing neurons in the lower thoracic level project at least partly to the gastric wall and the celiac ganglion. These results indicate that the diaphorase-positive ganglionic neurons in the thoracicolumbar levels may carry autonomic visceral afferent information. Double staining with NADPH-diaphorase histochemistry and peptide immunohistochemistry revealed that NADPH-diaphorase colocalizes with calcitonin gene-related peptide and substance P in many of these visceral afferent neurons.

Variations in blood flow on mandibular glandular secretion to autonomic nervous stimulations in anaesthetized dogs.

1. Continuous stimulation of the preganglionic parasympathetic nerve (the ramus communicans of the mandibular ganglion) for 1-2 min at supramaximal voltage (5 V) and pulse duration (1 ms) increased salivary gland arterial inflow and this was accompanied by copious salivary secretion. The responses were recorded continuously during the period of stimulation. The frequency for initiating the responses was 0.5 Hz. Maximal responses occurred at 16 Hz. The response coefficient of arterial inflow to stimulus frequency was 0.17 ml min-1g-1 Hz-1 and that of secretion to stimulus frequency was 0.016 ml min-1g-1 Hz-1. 2. The secretory response to low and moderate levels of parasympathetic nerve stimulation (below 8 Hz) was not affected by a reduction or cessation in arterial inflow whereas the response to high level parasympathetic nerve stimulation (above 8 Hz) was significantly alleviated if blood flow to the gland was maintained (via controlled vascular perfusion) at a level less than that of the resting arterial inflow. However, when the gland was already secreting near-maximally (stimulated at 8 Hz), sudden cessation of blood flow for a short period of time (0.5-2 min) had no effect on the salivary flow. 3. Continuous stimulation of the cervical sympathetic nerve for 1-2 min at supramaximal voltage (20 V) and pulse duration (1 ms) decreased arterial inflow and this was accompanied by scanty salivary secretion. The vascular response persisted during the period of stimulation. The secretory response was 15 s late in onset and might continue for 1 min after stimulation. The frequency for initiating the responses was 1-4 Hz. Maximal responses occurred at 16-32 Hz. The response coefficient of arterial inflow to stimulus frequency was -0.04 ml min-1g-1Hz-1 and that of salivary secretion to stimulus frequency was 0.001 ml min-1g-1Hz-1. 4. The secretory response to sympathetic nerve stimulation at different frequencies in glands with blood flow maintained at resting rate (via controlled vascular perfusion) resembled that in glands with spontaneous blood flow. 5. Sympathetic nerve stimulation was found to retard salivary secretion caused by parasympathetic stimulation, irrespective of whether the gland received spontaneous arterial inflow or controlled vascular perfusion at a resting flow rate. 6. The results suggest that the salivary secretion to stimulation of parasympathetic nerve is independent of blood flow over a wide range of stimulus frequencies; however, the response to high frequency stimulation of the parasympathetic nerve may be affected by fluctuations in blood flow.(ABSTRACT TRUNCATED AT 400 WORDS)

Nerves and nerve plexuses of the human vertebral column

The origin, distribution, and termination pattern of nerves supplying the vertebral column and its associated structures have been studied in the human fetus by means of an acetylcholinesterase whole-mount method. The vertebral column is surrounded by ventral and dorsal nerve plexuses which are interconnected. The ventral nerve plexus consists of the nerve plexus associated with the anterior longitudinal ligament. This longitudinally oriented nerve plexus has a bilateral supply from many small branches of the sympathetic trunk, rami communicantes, and perivascular nerve plexuses of segmental arteries. In the thoracic region, the ventral nerve plexus also is connected to the nerve plexuses of costovertebral joints. The dorsal nerve plexus is made up of the nerve plexus associated with the posterior longitudinal ligament. This nerve plexus is more irregular and receives contributions only from the sinu-vertebral nerves. The sinu-vertebral nerves originate from the rami communicantes and, in the cervical region, also from the nerve plexus of the vertebral artery. Thick and thin sinu-vertebral nerves are found. Most frequently three types of thick sinu-vertebral nerves are observed, i.e., ascending, descending, or dichotomizing ones. Finally, the distribution of the branches of the ventral and dorsal nerve plexuses and of the sinu-vertebral nerves is described.

Proximal communication between the glossopharyngeal and facial nerves.

The facial nerve branch termed Ramus communicans cum nervo glossopharyngeo in the current Nomina anatomica was investigated in 245 Japanese, especially as regards the frequency and pertinence as an approved definition. The communication was found in only 18.8%. It runs, if present, either medially, laterally or through the digastric posterior muscle. Teasing examination reveals that it always originates from the ninth nerve instead of the seventh and that it is destined to the back of the pinna. Its terminal bundle leaves the seventh nerve somewhat distally than the posterior auricular nerve in many examples, but the communication is likely to represent the auricular branch of the ninth nerve. As an offshoot of the seventh nerve, it is ill-defined, and should be affiliated to the ninth nerve in the Nomina anatomica. If it pierces the digastric muscle, half examples certainly give additional innervation to this muscle, but the fundamental disposition of the communication itself is not affected.

Differential projections of B and C sympathetic axons in peripheral nerves of the bullfrog.

Accumulating evidence indicates that electrophysiologically distinct subsets of sympathetic neurons selectively innervate different classes of targets. The organization of this system may therefore be reflected in the sympathetic fiber contents of peripheral nerves. To test this possibility, we have mapped the pathways followed by three groups of postganglionic sympathetic axons in the bullfrog by recording compound action potentials and by retrograde tracing with horseradish peroxidase (HRP). The axons that were studied arise from fast B, slow B, and C-type neurons in ganglia 9 and 10 at the lumbar end of the paravertebral sympathetic chain. They project to peripheral targets primarily by way of the sciatic nerve and can be distinguished by the velocities with which they conduct action potentials. Action potentials were recorded with suction electrodes from isolated preparations composed of paravertebral chain ganglia 7-10, the sciatic nerve, and branches of the sciatic nerve that supply striated muscles, skin, and the bladder. Preganglionic B fibers were selectively activated by stimulating the paravertebral chain rostral to ganglion 7, and preganglionic C fibers were selectively activated by stimulating spinal nerves 7 and 8 at points central to their rami communicantes. Compound action potentials recorded from the sciatic, peroneal, tibial, and sural nerves and from the primary trunk of the pelvic nerve were each found to contain three components produced, respectively, by fast B, slow B, and C-type sympathetic axons. Similarly, action potentials recorded from cutaneous branches of the sciatic tree were found to contain three sympathetic components. By contrast, when compound action potentials were recorded from branches of the sciatic tree that directly enter and innervate striated muscles and also the bladder, the sympathetic responses were found to arise solely from C-type axons. HRP was used to label the sympathetic neurons that project to the sartorius muscle and into the cutaneous lateral crural nerve. Retrograde transport of HRP from the sartorius muscle labeled 17 +/- 4 (mean +/- s.d.) sympathetic neurons and 27 +/- 3 spinal motoneurons while transport from the lateral crural nerve labeled 68 +/- 47 sympathetic neurons but no spinal neurons. The average somatic diameter of ganglion cells projecting to the sartorius muscle was significantly smaller than that of cells projecting to the lateral crural nerve. The electrophysiological results indicate that fast B and slow B sympathetic axons in the sciatic trunk and its primary branches project selectively into cutaneous nerves while sympathetic C axons project into all peripheral nerves.(ABSTRACT TRUNCATED AT 400 WORDS)

Sympathetic and afferent somata projecting in hindlimb nerves and the anatomical organization of the lumbar sympathetic nervous system of the rat.

The anatomy of the sympathetic pathways from the spinal cord to the lumbar sympathetic trunk and the inferior mesenteric ganglion was studied systematically in the rat. Details of the arrangements of white and gray rami communicantes, sympathetic trunk ganglia, the intermesenteric nerve, and the lumbar splanchnic nerves are summarized. A modified nomenclature for the segmental ganglia of the paravertebral sympathetic chain is proposed. Cell bodies of sensory and sympathetic axons projecting to the skin and skeletal muscle of the rat hindlimb were labeled retrogradely with horseradish peroxidase (HRP) in order to study numbers, segmental distribution, and location of the somata of these neurons quantitatively. HRP was applied to the nerves supplying skeletal muscle (gastrocnemius-soleus, GS), hairy skin (sural, SU; saphenous, SA) and to a mixed nerve (tibial, TI). All sensory somata and 96.4% of the sympathetic cell bodies were located ipsilaterally. Sensory somata were commonly restricted to two adjacent dorsal root ganglia (usually L3-4 for SA; L4-5 for GS, TI; L5-6 for SU). Although the sympathetic somata were more widely distributed rostrocaudally (four to six segments), their maximum was always located one or two segments more cranially than the sensory outflow, i.e., corresponding to the rami communicantes grisei. From the data, it is estimated that 420 sympathetic and 530 afferent neurons project into GS, 590 and 3,610 into SU, 920 and 3,750 into SA, and 1,070 and 5,760 into TI. These absolute neuron numbers are compared with electron microscopic fiber counts from the literature.

Spinal origins of preganglionic B and C neurons that innervate paravertebral sympathetic ganglia nine and ten of the bullfrog.

These experiments were designed to characterize the distribution, morphology, and number of spinal preganglionic neurons that selectively innervate the B- and C-type sympathetic neurons in paravertebral ganglia 9 and 10 of the bullfrog. For this purpose, horseradish peroxidase (HRP) was applied to the anterior end of the sectioned sympathetic chain between ganglia 8 and 9. Subsequent retrograde axonal transport of the HRP labeled ipsilateral spinal neurons whose cell bodies form a column having rostral and caudal boundaries that are, respectively, just caudal to the level of spinal nerve 4 and midway between the entry zones of spinal nerves 7 and 8. In all segments, the labeled preganglionic somata were found in the lateral half of the spinal gray and slightly dorsal to the central canal; a position analogous to that of the intermediolateral cell column in mammals. Most labeled preganglionic neurons were multipolar in shape, and the cell bodies lying between spinal nerves 4 and 5 were, on average, larger than those found between spinal nerves 7 and 8. In transverse sections that were cut near spinal nerve 5, the axons of preganglionic neurons could be seen to exit the cord through ventral roots. Counts of labeled preganglionic neurons indicate that an average +/- S.D. of 338 +/- 89 cells innervate ganglia 9 and 10. Selective labeling of preganglionic B neurons, by cutting spinal nerves 7 and 8 central to their rami communicantes at the time of HRP application, revealed an average +/- S.D. of 137 +/- 31 cells that lie exclusively between spinal nerves 4 and 6. By contrast, selective labeling of preganglionic C neurons, by cutting the sympathetic chain rostral to ganglion 7 at the time of HRP application, revealed an average +/- S.D. of 187 +/- 77 cells in an adjacent portion of the preganglionic column that is bounded by spinal nerve 6 and by a point midway between spinal nerves 7 and 8. These results thus demonstrate a clear segmental segregation between the preganglionic B and C neurons that innervate ganglia 9 and 10.

Thoracic sympathetic trunk compression by osteophytes associated with arthritis of the costovertebral joint. Anatomical and clinical considerations.

Hyperostosis (lipping) due to costovertebral arthritis was found frequently (84.3%) impinging on the sympathetic trunks (ganglia and cord), rami communicantes and roots of the splanchnic nerves on both sides of the spine in more than 1,000 dissecting room cadavers examined and 34 cadavers of adult and elderly people specially dissected. As a result of the compression, the affected sympathetic structures were angulated, deflected from their course, enlarged and often infiltrated with connective tissue. The possible symptoms which may result from this kind of compression are discussed.

Branches of the thoracic sympathetic trunk in the human fetus.

The segmental organization of the thoracic sympathetic trunk and all its ramifications was studied in 6 human fetuses (16-22 weeks) by means of the acetylcholinesterase in toto staining method. Each trunk was divided into 12 sympathetic segments. A segment is defined as that part of the sympathetic trunk which is connected via its rami communicantes with one spinal nerve, without discriminating between grey and white rami. The diameter of the rami communicantes and their direction towards the spinal nerves are variable. The number of peripheral segmental ramifications of the trunk is much larger than assumed previously. Each thoracic sympathetic segment gives off at least 4-5 nerves. Three categories of nerves are discerned: (1) large splanchnic rootlets confined to the greater, lesser and least thoracic splanchnic nerves, (2) medium-sized splanchnic nerves directed towards thoracic viscera, some of which give off branches towards costovertebral joint plexuses and, described for the first time in man, (3) small nerves which ramify extensively and form nerve plexuses in the capsule of the costovertebral joints. The majority of the ramifications is formed by the nerves of the third category. The existence of Kuntz's nerve, connecting the 2nd intercostal nerve and 1st thoracic spinal nerve, is confirmed in four specimens. The nerve plexuses of the costovertebral joints receive a segmentally organized innervation: they receive their input from the neighbouring sympathetic segment and the one cranial to it. It is concluded that the thoracic sympathetic branches in man show a complex, segmentally organized pattern and may have a considerable component of somatosensory nerve fibers. The complex relationships must be taken into account in surgical sympathectomies.

Osteophytes of the spine compressing the sympathetic trunk and splanchnic nerves in the thorax.

The presence of osteophytes compressing the sympathetic structures in the thorax was found in 655 (65.5%) of 1,000 cadavers. In 60.4% of the affected cases, the compression was on the right side, and in 36.9% it was bilateral, although the right side was more severely affected. In 2%, the compression was on the left only. The highest frequency of compression was at the T8-10 level, the right greater splanchnic nerve being the structure most frequently involved. The sympathetic trunk itself (ganglia and cord) was affected only by osteophytes of vertebrae at the lowest thoracic levels; however, bony excrescences due to costovertebral joint arthritis were frequently found impinging on the sympathetic trunk and its rami communicantes at similar frequencies on both sides. The factors governing the characteristic compression of the sympathetic structures in the thorax are the typical development of the osteophytes and the special relations of the sympathetic structures to the vertebral column at the various levels. It is proposed that these observations are useful in understanding certain observed clinical conditions and act an anatomic baseline for research in the future.

Cholinergic excitatory synaptic potentials of neurones in mammalian lumbar paravertebral ganglia

Synaptic potentials and the electrophysiological properties of 201 cells in the 4th lumbar paravertebral ganglia of the rabbit were studied in vitro using intracellular electrophysiological recording techniques. Cells had a mean transmembrane potential of 55.1 ± 0.8 mV, a mean input resistance of 37.0 ± 6.6 M Ω (range 29.9–61.1) and a mean membrane time constant of 6.0 ± 0.6 ms. Synaptic potentials in ganglionic neurones were evoked by electrical stimulation of the rami communicantes, inferior lumbar splanchnic nerves and the paravertebral chain from segments both above and below the L 4 ganglion. Synaptic responses consisted of a fast, hexamethonium-sensitive component and, following short periods of higher frequency stimulation, a slow, long lasting, pirenzepine and atropine-sensitive depolarization (slow-EPSP). No phenomenon corresponding to a late slow-EPSP was observed and, under our recording conditions no cells exhibited non-cholinergic slow excitatory or slow inhibitory postsynaptic potentials. It is concluded that fast excitatory synaptic events were mediated by nicotinic receptors whereas slow excitatory synaptic events were mediated by muscarinic m l receptors. McNeil-A-343, a muscarinic agonist, produced membrane depolarization, a decrease in membrane input conductance and in some cells a repetitive discharge of action potentials. In 60% of cells tested substance P produced a depolarization of the membrane potential with an associated decrease in membrane input conductance.

Cardiovascular reflexes mediated by capsaicin sensitive cardiac afferent neurones in the dog

Reflex circulatory changes mediated by capsaicin sensitive cardiac afferent neurones were studied in anaesthetised, open chest dogs. Application of capsaicin to the epicardium of the left ventricle, either in single doses (0.01-100 micrograms) or by superfusion (20 micrograms X min-1), consistently resulted in dose related increases in blood pressure and heart rate. These responses were not affected by bilateral vagotomy but were abolished or reversed by bilateral sectioning of the upper thoracic (T1-T4) white rami communicantes and stellectomy. Injection of capsaicin (0.3-1 microgram X kg-1) into the left circumflex coronary artery caused either systemic hypotension and bradycardia (70.3% of experiments), a pressor response associated with tachycardia (13.5%), or a biphasic effect with an initial rise and then fall in blood pressure and heart rate (16.2%). With intravenous injections of capsaicin (3-5 micrograms X kg-1) the response was invariably cardioinhibitory and depressor. The reflex bradycardia and hypotension evoked with either intracoronary or intravenous injections of capsaicin were reversed after bilateral vagotomy to increases in cardiac rate and blood pressure. The post-vagotomy tachycardia occurring with intracoronary capsaicin could be abolished by beta adrenoceptor blockade with propranolol (0.5 mg X kg-1 iv), whereas ganglionic transmission blockade with pentolinium (0.5 mg X kg-1 iv) eliminated both the tachycardia and pressor effects. The results indicate that in the dog's heart capsaicin sensitive afferent neurones capable of affecting the circulatory system have both vagal and spinal sympathetic origin. It is suggested that capsaicin induced excitatory cardiogenic reflex is nociceptive in nature and may involve activation of substance P containing afferent fibres incorporated in cardiac sympathetic nerves.

The location and characteristics of sympathetic preganglionic neurones in the lower thoracic spinal cord of dog and cat.

The retrograde transport of horseradish peroxidase from a white ramus communicans has been used to define the precise segmental location of sympathetic preganglionic cell bodies in the spinal cord of the cat and dog. All labelled cells were found ipsilaterally and were confined to the spinal cord segment from which the ramus originated. Most lay in the intermediolateral cell column and the immediately adjacent white matter, though others were scattered in more medial areas of the grey matter. We suggest that the observed distribution of sympathetic preganglionic neurones, the orientation of their processes and the paths taken by their axons are a direct result of cell migration during the embryological development of the spinal cord.

Effects of propranolol on the impulse activity of cardiovascular sympathetic afferent fibers.

The influence of beta-adrenergic receptor blockade on the impulse activity of 21 cardiovascular sympathetic afferent nerve fibers (11 from the thoracic aorta, 10 from the pulmonary veins), isolated from the left sympathetic rami communicantes T-3 and T-4 was studied in anesthetized, vagotomized cats. Aortic pressure, heart rate, and neural discharge were recorded during control conditions and during brief aortic occlusions of comparable amplitude and duration. Administration of dl-propranolol (0.2-0-4 mg/kg) did not modify aortic pressure or neural discharge of the fibers during control conditions, although, as expected, heart rate was diminished. dl-Propranolol administration did change the response of cardiovascular sympathetic afferents to similar aortic pressure increases. Before drug administration, aortic occlusion caused a significant increase in neural discharge of both aortic and pulmonary vein sympathetic afferent fibers, from 0.52 +/- 0.12 to 1.64 +/- 0.31 and from 0.67 +/- 0.10 to 2.08 +/- 0.25 impulses/sec, respectively (p less than 0.05). After dl-propranolol administration, comparable increases in aortic pressure resulted in slight but not significant increases in neural discharge of aortic and pulmonary vein fibers. Administration of d-propranolol (0.4-0.6 mg/kg), which possesses only membrane-stabilizing properties, did not modify the firing rate of four pulmonary sympathetic afferents, which subsequently decreased their response to pressure rises after administration of dl-propranolol. These results indicate that beta-adrenergic receptor blockade reduces the responsiveness to hemodynamic stimuli of sympathetic cardiovascular afferent fibers that are capable of mediating excitatory pressor reflexes.

Development of the innervation of the urogenital complex in the fetal mouse.

The developing urogenital complex of the fetal mouse was studied by means of silver impregnation and electron microscopy. These studies showed that: 1) the mesonephric field is innervated during prenatal stages (Wolffian nerve); 2) nerve penetration precedes the differentiation of the gonads and related ducts; and 3) the Wolffian nerve arises during the earliest stages from the first pair of abdominal rami communicantes. The identity between the fetal Wolffian nerve and the nerve of the suspensory ligament (higher pathway) of the adult is discussed.

Degeneration patterns of postganglionic fibers following sympathectomy.

In cats the time course of degeneration following lumbal sympathectomy was studied in the ramus communicans griseus (rcg) and in the nerves to the triceps surae muscle using light and electron microscopic methods. The left lumbar sympathetic trunk including its rami communicantes was removed from L2 to S1 using a lateral approach. The animals were sacrificed between 2 and 48 days after the sympathectomy. Tissue samples were taken (a) one cm proximal to the entrance of the rcg into the spinal nerve, and (b) one cm proximal to the entrance of the nerve into the muscle belly. In the rcg signs of degeneration can already be recognized in the myelinated as well as in the unmyelinated axons 48 h after sympathectomy. The degenerative processes in the axons reach their peak activity at about 4 days p.o. They end a week later. Signs of the reactions of the Schwann cells and of the endoneural cells can first be seen 2 days p.o. They are most pronounced around the 8th day p.o., and last at least up to the third week. Thereafter the cicatrization processes settled to a rather steady state (total observation period 7 weeks). In the muscle nerves the first signs of an axonal degeneration of the sympathetic fibers can be recognized 4 days after surgery. The signs of axonal degeneration are most striking about 8 days p.o. They have more or less disappeared another week later. The reactions of the Schwann cells also start on the fourth day but outlast the degenerative processes by some 8 days. Thus the degenerative and reactive processes in the rcg precede those in the muscle nerves by 2 days early after surgery and by 6 days 3 weeks later. Seven weeks after surgery, fragments of folded basement lamella and Remak bundles with condensed cytoplasm and numerous flat processes are persisting signs of the degeneration. In addition to the differences in time course between the proximal and the distal site of observation, it was also noted that both the axonal degeneration and the reactions of the Schwann cells are more pronounced in the rcg than in the muscle nerve. For example there was abundant mitotic activity in the central endoneural and Schwann cells whereas we could not detect such activity in the periphery.(ABSTRACT TRUNCATED AT 400 WORDS)