Inferior Ganglion Research Articles

The Social Brain: Social Scientists' Construct or Neurological Reality?A review of The Oxford Handbook of Social Neuroscience. Oxford Library of Psychology. Edited by Jean Decety and John T. Cacioppo. Oxford and New York: Oxford University Press. $250.00. xxiii + 1099 p.; ill.; author and subject indexes. ISBN: 978-0-19-534216-1. 2011.

The Social Brain: Social Scientists' Construct or Neurological Reality?<i>A review of The Oxford Handbook of Social Neuroscience. Oxford Library of Psychology</i>. Edited by Jean Decety and John T. Cacioppo. Oxford and New York: Oxford University Press. $250.00. xxiii + 1099 p.; ill.; author and subject indexes. ISBN: 978-0-19-534216-1. 2011.

Progressive Facial Paralysis Secondary to a Rare Temporal Bone Tumor&lt;subtitle&gt;Glomus Faciale&lt;/subtitle&gt;

P aragangliomas are slow-growing benign neoplasms arising from foci of neural crest– derived chemoreceptor tissue, paraganglia. Paragangliomas are most often discovered based on mass effect on nearby structures and are rarely functional outside of the adrenal gland. In the head and neck, paraganglia most commonly reside at the carotid bifurcation, the inferior ganglion region or cervical portion of the vagus nerve, the jugular bulb, and the middle ear cavity; thus, most are discovered in these locations. In the skull base, paraganglia in the area of the jugular bulb and along the cochlear promontory make glomus tympanicum and glomus jugulare the most frequently encountered paragangliomas. Although these 2 tumors are relatively common in the temporal bone, a primary paraganglioma of the fallopian canal, or glomus faciale, is rare. In fact, to our knowledge, only 8 reports exist. We describe the presentation, workup, and treatment of the ninth report in the literature.

A Case of Glomus Vagale Tumor with the Complaint of Hoarseness

Dear Editor, Vagal paragangliomas are uncommon tumors of the parapharyngeal space, approximately 200 cases having been reported.[1] They arise from tissue of the extra adrenal sympathetic nervous system.[2] They mostly manifest as a painless neck mass near the angle of the mandible usually between the skull base and the hyoid bone.[3] The other manifestations are hoarseness and less commonly dysphagia, palatal weakness and tongue hemi-atrophy.[1][4] Pressure on the cervical sympathetic chain causes horner syndrome. Ultrasonography, CT scan, MRI and angiography are diagnostic modalities been used, but combining conventional MR imaging with CE-MRA has dramatic diagnostic value for the assessment of head and neck paragangliomas.[5] Surgical resection is the treatment for carotid body tumors, and the procedure should be undertaken unless the patient has a prohibitive operative risk.[4] Here we present a rare glomus vagale case presented with hoarseness and show his management. A 37 years old farmer presented with hoarseness and left cervical mass beyond mandible angle. He did not claim of another symptom, on physical examination a firm mobile 2x2 cm mass was moving horizontally. Before treatment planning, we found left vocal cords paralyzed and CT scan demonstrated a heterogenous lesion next to the carotid bifurcation (Figure 1). Planning resection, he underwent surgery and we found two masses, one in 1.5x1.5 over bifurcation and the other just in bifurcation area extending toward skull through vagal foramen, we could resect these highly vascular masses while saving carotid branches but sacrificing involved vagal nerve. Pathologist confirmed these paragangliomas. Fig. 1 CT scan shows left neck mass. The normal carotid body is a small mass of neurovascular tissue located bilaterally in the medial valley of the carotid artery bifurcation. Although the term has historically been assigned to these masses, they are not carcinomas, and the neoplastic process is actually hypertrophy of the carotid body tissue.[6] The four main locations of glomus tissue within the head and neck are: (a) The carotid bifurcation (carotid body tumor), (b) The inferior ganglion region (ganglion nodosum) and cervical portion of the vagus nerve (glomus vagale or vagal paraganglioma), (c) The jugular bulb region (glomus jugulare) and (d) The middle ear cavity (glomus tympanicum).[3] Paragangliomas originate in the head and neck from the brachiomeric family of paraganglia, neuroendocrine tissue which lies along the carotid artery, the aorta, the glossopharyngeal nerve, and the middle ear.[7] Preoperative planning requires a selective carotid arteriogram to clarify arterial anatomy and the relation of the carotid body tumor to the carotid bifurcation. Embolization of the tumor may also be achieved through these branch vessels, particularly in cases in which the lesion extends over a considerable distance and may approach the base of the skull. Challenging options about surgical versus radiation treatment continues, advocating radiation for small lesions,[8][9] and surgery in younger patients and tumors causing bony destruction.[10] Morbidity associated with vagal paraganglioma surgery is significantly higher than that of carotid body tumor surgery. Plans for intraoperative blood cell salvage are appropriate, as significant blood loss is routine in the dissection of these lesions.[6] Therapeutic embolization reduces the size of the tumor and limits intraoperative blood loss but may rarely be considered as definitive treatment.[11] Radiation therapy is an alternative to surgery and may be effective in arresting the growth, but it can lead to neurologic sequelae and rarely can destroy the tumor. Irradiation is generally used in elderly patients as well as in large and unresectable tumors [1] and gathering data upon clinical examination and imaging, we prepared our client to surgery. Under general anesthesia via standard cervical approach, tumor dissected off the carotid branches but found left vagus nerve involved, extending toward skull base through cranial nerve foramen, so had to sacrify it.

The Jugular Foramen: Imaging Strategy and Detailed Anatomy at 3T

The purpose of this study was to assess how well the anatomy of the jugular foramen (JF) could be displayed by 3T MR imaging by using a 3D contrast-enhanced fast imaging employing steady-state acquisition sequence (CE-FIESTA) and a 3D contrast-enhanced MR angiographic sequence (CE-MRA). Twenty-five patients free of skull base lesions were imaged on a 3T MR imaging scanner using CE-FIESTA and CE-MRA. Two readers analyzed the images in collaboration, with the following objectives: 1) to score the success with which these sequences depicted the glossopharyngeal (CNIX) and vagus (CNX) nerves, their ganglia, and the spinal root of the accessory nerve (spCNXI) within the JF, and 2) to determine the value of anatomic landmarks for the in vivo identification of these structures. CE-FIESTA and CE-MRA displayed CNIX in 90% and 100% of cases, respectively, CNX in 94% and 100%, and spCNXI in 51% and 0% of cases. The superior ganglion of CNIX was discernible in 89.8% and 87.8%; the inferior ganglion of CNIX, in 73% and 100%; and the superior ganglion of CNX, in 98% and 100% of cases. Landmarks useful for identifying these structures were the inferior petrosal sinus and the external opening of the cochlear aqueduct. This study protocol is excellent for displaying the complex anatomy of the JF and related structures. It is expected to aid in detecting small pathologies affecting the JF and in planning the best surgical approach to lesions affecting the JF.

Tyrosine hydroxylase-immunoreactive fibers in the human vagus nerve

Sympathetic catecholaminergic fibers in the vagus nerve were immunohistochemically examined in formalin-fixed human cadavers using an antibody against the noradrenalin-synthetic enzyme tyrosine hydroxylase (TH). TH-positive fibers were extensively distributed in the vagal nerve components, including the superior and inferior ganglia, the main trunk and the branches (superior and recurrent laryngeal, superior and inferior cardiac, and pulmonary branches). The inferior ganglion and its continuous cervical main trunk contained numerous TH-positive fibers with focal or diffuse distribution patterns in each nerve bundle. From these findings, we conclude that sympathetic fibers are consistently included in the human vagus nerve, a main source of parasympathetic preganglionic fibers to the cervical, thoracic and abdominal visceral organs.

Jugular Foramen Schwannoma

To examine the microsurgical anatomy of the jugular foramen and correlate anatomical findings to clinical manifestations of jugular foramen schwannomas concerning tumor origin and location. Anatomical analysis of jugular foramen was performed by dissection of 25 cadavers (50 sides). By retrospective review of 9 cases of jugular foramen schwannomas surgically treated, the origin and location of tumor were studied. Tertiary referral center. The anatomical characteristics of jugular foramen, lower cranial nerves, and inferior petrosal sinus were correlated with the origin and growth pattern of jugular foramen schwannomas. The superior and inferior ganglions of the glossopharyngeal nerve and the superior ganglion of the vagus nerve were located within the jugular foramen. The superior ganglions of the glossopharyngeal and vagus nerves were located superiorly, whereas the inferior ganglion of the glossopharyngeal nerve was found inferiorly in relation to the inferior petrosal sinus orifice. In our series of 9 cases of jugular foramen schwannoma, the most common nerve of origin was the vagus nerve, followed by the glossopharyngeal nerve. The reason for the predilection of the jugular foramen schwannoma for the glossopharyngeal and vagus nerves may be associated with the presence of their ganglions within the jugular foramen. Also, the inferior petrosal sinus may act as a barrier to tumor growth, and the location of the ganglion of tumor origination within the jugular foramen in relation to the inferior petrosal sinus may be correlated to the predominant direction of tumor extension.

Nerve fiber analysis of ansa cervicalis–vagus communications

Communications between the ansa cervicalis and the vagus nerve, although described only as variations in many textbooks, can be observed frequently in the dissection room. Following macroscopic observation, some of such cases were subsequently dissected under surgical microscope to determine the nature of such communications. As a result, two broad categories of communications between the ansa cervicalis complex and the vagus nerve could be recognized: (i) false (pseudo) communications, where the two nerves were attached only by the connective tissue with no fiber exchange; and (ii) true communications, with nerve fiber involvement. Fiber analysis showed that the majority of the ansa-vagal communications observed during gross dissection were of the first category. True communications, when present, were only scanty contributions and always directed towards the side of the vagus. In addition, the vagus (region of the inferior ganglion) and hypoglossal nerves were found to be in close contact at the base of the skull and usually could not be separated by gross dissection. But such attachments, too, were shown to be almost entirely of false nature except for the possible presence of a few fine nerve filaments. It seems that the ansa-vagal communications are merely a result of the close physical relationship between the two structures and serve no significant functional purpose, but at the same time may hinder the prospects of using ansa cervicalis in surgical procedures such as re-innervation of laryngeal and facial muscles, following damage to recurrent laryngeal and facial nerves, respectively.

Head and Neck Pathology–Radiology Classics: Vagal Paraganglioma

Paragangliomas are tumors arising from extra-adrenal paraganglia and are present throughout the body. Paragangliomas—also called chemodectomas—of the head and neck are the most common of all paragangliomas. They are rare with an incidence of 0.2–1/100.000. They may originate from carotid body, vagal body, middle ear, and larynx. The ones of vagal origin represent less than 5%. Vagal paragangliomas originate within the first 2 cm of the extracranial stretch of the vagus nerve and are associated with the inferior ganglion. Vagal paragangliomas, as other paragangliomas of the head and neck most commonly present as masses, but may cause other symptoms, such as tinnitus or hoarsness or cranial nerve paralysis. They may present as singular tumors or multiple paragangliomas. Most multiple cases are associated with a family history (MEN IIA and MEN IIB, von Hippel-Lindau syndrome and other, rarer entities). Although they might have a secretory product, usually they are hormonally inactive. Radiographically the tumor appears as a well-circumscribed, homogeneously- and intensely-enhancing mass on CT. On MRI, the mass is iso- to slightly hyperintense to muscle on T1-weighted imaging, and slightly hyperintense to muscle on T2-weigted imaging. Multiple, branching flow voids are typically seen within the tumor on both T1- and T2-weighted images. On T2-weighted imaging, the punctate black flow voids in cross section within the relatively bright tumor create a characteristic “salt and pepper” appearance in tumors over 2 cm in maximal diameter. Additionally, flow voids of large feeding arteries are seen at the periphery of the mass. Angiography demonstrates the characteristic appearance of a vascular tumor with large feeding arteries, intense tumor stain, and early draining veins (Fig. 1A–D). Fig. 1 (A) Angiography. Lateral view (patient’s face is on left side of image) of the arterial phase of a digital subtraction angiogram with left common carotid artery injection shows early, intense enhancement of a vascular mass (arrow) that is causing ... Grossly the tumor is encapsulated ovoid mass with tan to red-brown cut surface. Histologically, the tumors have a characteristic organoid growth pattern, consisting of two cell populations: chief cells arranged in a ball-like fashion (zellballen—German for cell balls) and sustentacular cells surrounding them (Fig. 2). Chief cells are of neural crest origin. They have abundant amphophilic, slightly granular cytoplasm and central nuclei. Nuclear pleomorphism is variable, occasionally striking; however, its presence is not indicative of aggressive behavior. The cytoplasm contains neurosecretory granules, consequently the cells react with neuroendocrine markers, such as chromogranin, synaptophysin and CD 56. Sustentacular cells are inconspicuous, spindle shaped cells surrounding the “zellballen”. They are believed to be modified Schwann cells, have a supporting role and react with S-100 (Fig. 3). As other neuroendocrine tumors, paragangliomas are highly vascular neoplasms. Fig. 2 Histology, H&E, 20×. Note the organoid growth pattern with zellballen and the rich vasculature in the delicate septa between them Fig. 3 (A) Chromogranin immunostain, 40×. Chief cells forming the zellballen react with Chromogranin A, while the surrounding sustentacular cells are negative (left). (B) S100 immunostain, 40×. As a mirror image, sustentacular cells react with ... Most paragangliomas are benign; however, there are no definite criteria for malignancy other than the presence of metastatic disease. The presence of capsular or vascular invasion and necrosis may be indicative of malignancy. Differential diagnosis includes hemangiopericytoma, neuroendocrine carcinomas, alveolar soft part sarcoma, metastatic medullary carcinoma of the thyroid and metastatic renal cell carcinoma. The vascular component of the tumor occasionally shows wide, branching, staghorn-like architecture, reminding of hemangiopericytoma. Hemangiopericytoma lacks the organoid growth pattern with zellballen and the immunohistochemical characteristics are different. Metastatic medullary carcinoma is a logical option on the neck, moreover the growth pattern may be similar and both react with neuroendocrine markers. However, medullary thyroid carcinoma often produces amyloid, which is not a characteristic of paraganglioma and reacts with calcitonin that is not expressed by paragangliomas. The alveolar growth pattern of alveolar soft part sarcoma and some renal cell carcinomas may mimic the zellballen, but the latter are much smaller units and have two distinct types of cells. Neuroendocrine carcinomas may have an organoid growth pattern, but they are usually malignant looking neoplasms with high mitotic rate and lack the S100 positive sustentacular cell component. Therapeutic options include surgery, radiotherapy and stereotactic radiosurgery. The vascular nature of the tumor makes surgery difficult sometimes—this can be reduced with preoperative chemoembolization.

Superior laryngeal nerve anatomy in corpses not preserved in formaldehyde: contribution to the operative technique

To carry out an anatomic study of superior laryngeal nerve in not preserved in formaldehyde and not frozen corpses. Thirty-eight male corpses from the Minas Gerais Medico-legal Institute (IML) were studied. In 18 corpses dissection was performed bilaterally and in 20 only on the left side, total number 56 nerves dissected. Their descriptive segments measurements and the anatomic relations with the cervical structures of the region were described. This nerve was statistically analyzed; the variables were corpse side (Friedman's test (p<0.05), height (Pearson), racial group (Kruskal-Wallis). The superior laryngeal nerve presented a definite anatomical disposition in all the 56 nerves studied, emerging from the nervus vagus inferior ganglion. The superior laryngeal nerve trunk was in average longer in corpses over 25 years old (p<0.05). Significant differences (p<0.05) between the internal and external branches were observed in all racial groups, and the internal branch average was inferior to the external branch average. There were not significant differences between the 18 studied corpses' left and right sides paired measurements. Concerning emergence, trunk, bifurcation and major branches, the 56 studied nerves disposition had a definite anatomic pattern. The superior laryngeal nerve trunk was in average longer in corpses over 25 years old. In this study, the external branch of the laryngeal nerve was in average longer than the internal branch.

The Role of Neuron Numbers of the Petrosal Ganglion in the Determination of Blood Pressure: An Experimental Study

Baroreceptor reflexes are regulated by nerve terminals of the glossopharyngeal and vagal nerves. The body of pressure-sensitive neurons of these nerves is located in the petrosal ganglion of both nerves. We examined whether there is a relationship between the neuron numbers of the inferior ganglion of the glossopharyngeal nerve and blood pressure values. Petrosal ganglions were examined in 18 male hybrid rabbits divided into three equal groups: Group A normotensive (TA=90-100 mmHg), Group B hypertensive (TA>100 mmHg); and Group C hypotensive (TA<90 mmHg). After examination of blood pressure for one week, all animals were sacrificed, and the petrosal ganglions extracted bilaterally and examined histopathologically using the physical dissector method. The mean (+/-SD) neuronal density was: Group A 8700+/-200, Group B 7800+/-250 and Group C 9800+/-300, respectively. The difference between the groups B and C as compared to A was significant (p<0.01) while the difference between Groups B and C was highly significant (p<0.001). An inverse relationship was noticed between the neuronal density in the petrosal ganglion and blood pressure values with potential implications in the study of the etiology of hypertension.

Surgical anatomy of the cervical sympathetic trunk

Lack of knowledge of the anatomy of the cervical sympathetic trunk (CST) may complicate surgical procedures on the cervical spine. This study aims to define linear and angular relations of the CST with respect to consistent structures around it, including the number and size of the cervical ganglia, the distances between the CST and the longus colli muscle and the anterior tubercles of the transverse processes of cervical vertebrae. Morphometric parameters of the 24 CSTs of 12 adults were measured on both sides. The CST had superior, middle, and inferior (or cervicothoracic) ganglia in 20.8% of specimens; superior and inferior (or cervicothoracic) ganglia in 45.8%; superior, middle, vertebral, inferior, or cervicothoracic ganglia in 12.5%, and superior, vertebral, inferior or cervicothoracic ganglia in 20.8% of specimens. The superior ganglion was observed in all specimens, the middle ganglion and vertebral ganglion were each observed in 33.3%. There was no difference between the number of superior and vertebral ganglia between the right and left sides. The average distance between the CST and the medial border of the ipsilateral longus colli muscle (LCM) was 17.2 mm at C3 and 12.4 mm at C7. As the CSTs converged caudally, the LCMs diverged. The average distance between the anterior tubercles of transverse processes of the cervical vertebrae and the lateral borders of the ipsilateral CST was 3.4 mm at C4, 3.2 mm at C5, and 3.9 mm at C6. The presence of a vertebral ganglion and variations, such as the localization of the CST within the carotid sheath, are important. The anatomical landmarks described should assist the spinal surgeon to avoid injury of the CST.

Anatomic Landmarks of the Glossopharyngeal Nerve: A Microsurgical Anatomic Study: In Reply

OBJECTIVE: Compared with other lower cramal nerves, the glossopharyngeal nerve (GPhN) is well hidden within the juguiat furamen, at the infratemporal fossa, and in the deep layers of the neck. This study aims to disclose the course of the GPhN and point out landmarks to aid in its exposure. METHODS: The GPhN was studied in 10 cadaveric heads (20 sides) injected with colored latex for microsurgioal dissection The specimens were dissected under the surgical microscope. RESULTS: The GPhN can be divided into three portions, cisternal, jugular foramen, and extracranial. The roothes of the GPhN emerge from the postolivary sulcus and course ventral to the floccuius and choroid plexus of the lateral recess of the fourth ventricle. The nerve then enters the jugut foramen through the uppermost porus (pars nervosa) and is separated from the vagus and accorssory nerves by a fibrous crest. The cochlear aqueduct Opens to the roof of this porus. On foor sides in the cadaver specimens (20%), the GPhN traversed a separate bony canal within the jugular foramen; no separate canal was found in the other cadavers, in all specimens, the Jacobon's (tympanic) serve emerged from the inferior ganglion of the CPhN, and the Arnold's (auticalat brancht of the vagost nerve also consisted of branches from the GPhN. The GPhN revds from the juguiar foramen posteromedial to the styloid process and the styloiod muscles, The last four cranial nervres and the internal jugular vein pass through a narrow space between the transverse process of the altas (CT) and the styloid process. The styloid muscles are a pytamid shape, the tip of which is formed by the attachment of the styloid muscles to the styloid precess The GPhN crosses to the anterior side of the stylopharyngeus muscle at the junction of the shlopharyngeus, middle constictes, and hyoglossal muscles, which are at the base of the pyranid. The middle constrictor muscle formis a wall between the GPhN and the hypoglossal nerve in this region. Then, the GPhN gives off a lingual branch and deepens to innervate the pheryeal mucosa. CONCLUSION: Type landmarks help to identify the GPhN in the subarachnoid space, the choroid plessis of the lateral recess of the fourth ventricle and the dural entrance porus of the jugular foramen, The opening of the cochlear aqueduct, the mastoid canalicuius, and the inferior tympanic canalicultis are three landmarks of the GPhN within the jugular foramen. Finally, the base of the styloid process, the base of the styloid pyramid, and the transverse process of the atlay serve as three landmarks of the GPhN at the extracranial region in the infratemporal fossa.

Anatomic landmarks of the glossopharyngeal nerve: a microsurgical anatomic study.

Compared with other lower cranial nerves, the glossopharyngeal nerve (GPhN) is well hidden within the jugular foramen, at the infratemporal fossa, and in the deep layers of the neck. This study aims to disclose the course of the GPhN and point out landmarks to aid in its exposure. The GPhN was studied in 10 cadaveric heads (20 sides) injected with colored latex for microsurgical dissection. The specimens were dissected under the surgical microscope. The GPhN can be divided into three portions: cisternal, jugular foramen, and extracranial. The rootlets of the GPhN emerge from the postolivary sulcus and course ventral to the flocculus and choroid plexus of the lateral recess of the fourth ventricle. The nerve then enters the jugular foramen through the uppermost porus (pars nervosa) and is separated from the vagus and accessory nerves by a fibrous crest. The cochlear aqueduct opens to the roof of this porus. On four sides in the cadaver specimens (20%), the GPhN traversed a separate bony canal within the jugular foramen; no separate canal was found in the other cadavers. In all specimens, the Jacobson's (tympanic) nerve emerged from the inferior ganglion of the GPhN, and the Arnold's (auricular branch of the vagus) nerve also consisted of branches from the GPhN. The GPhN exits from the jugular foramen posteromedial to the styloid process and the styloid muscles. The last four cranial nerves and the internal jugular vein pass through a narrow space between the transverse process of the atlas (C1) and the styloid process. The styloid muscles are a pyramid shape, the tip of which is formed by the attachment of the styloid muscles to the styloid process. The GPhN crosses to the anterior side of the stylopharyngeus muscle at the junction of the stylopharyngeus, middle constrictor, and hyoglossal muscles, which are at the base of the pyramid. The middle constrictor muscle forms a wall between the GPhN and the hypoglossal nerve in this region. Then, the GPhN gives off a lingual branch and deepens to innervate the pharyngeal mucosa. Two landmarks help to identify the GPhN in the subarachnoid space: the choroid plexus of the lateral recess of the fourth ventricle and the dural entrance porus of the jugular foramen. The opening of the cochlear aqueduct, the mastoid canaliculus, and the inferior tympanic canaliculus are three landmarks of the GPhN within the jugular foramen. Finally, the base of the styloid process, the base of the styloid pyramid, and the transverse process of the atlas serve as three landmarks of the GPhN at the extracranial region in the infratemporal fossa.

Carotid body and glomus cells distributed in the wall of the common carotid artery in the bird.

In the bird the carotid body is located between the distal (nodose) ganglion of the vagus nerve and the recurrent laryngeal nerve at the beginning of the common carotid artery, that is, the organ is located at the cervicothoracic border. The chicken carotid body receives numerous branches from the vagus and the recurrent laryngeal nerves. In addition, dense networks of the peptidergic nerve fibers immunoreactive for substance P, calcitonin gene-related peptide (CGRP), vasoactive intestinal peptide (VIP), galanin, and neuropeptide Y (NPY) are distributed in and around the carotid body parenchyma. The substance P- and CGRP-immunoreactive fibers are derived from both the superior and inferior ganglia of the vagus nerve. The VIP-, galanin-, and NPY-immunoreactive fibers originate from the 14th cervical ganglion of the sympathetic trunk. The endocrine organs including the thyroid gland, parathyroid glands, carotid body, and ultimobranchial gland are situated as a continuous series along the common carotid artery. The organs are supplied with arteries arising as one trunk from the common carotid artery. Glomus cells are widely distributed not only in the carotid body but also in the wall of the common carotid artery and around the common trunk and its branches. The glomus cells of the chicken carotid body exhibit intense immunoreactivity for serotonin, tyrosine hydroxylase, and chromogranin A. The cells located in the wall of the common carotid artery further express NPY mRNA and peptide. In the chickens exposed to isocapnic hypoxia for 35 days, 3-4-fold increase of the carotid body volume is induced and the carotid body glomus cells show enhanced synthetic and secretory activities. On the other hand, the cells in the wall of the common carotid artery display little changes after the long-term hypoxia, having different functions from the carotid body. The carotid body rudiment is formed in the lateral wall of the third branchial artery. The neural cells immunoreactive for TuJ1, PGP 9.5, and HNK-1, which are continuous with the inferior vagal (nodose) ganglion, first surround and then invade both the carotid body rudiment and the other portions of the third branchial artery, becoming glomus cells.

Role of peripheral NMDA receptors in colorectal distension mediated afferent nerve activity: An In vitro study

BACKGROUND: NMDA receptors (NMDA-R) are expressed on the peripheral terminals of extrinsic afferent nerves innervating the rat colon, and NMDA-R antagonists, acting peripherally, inhihit hehavioral pain responses to colorectal distension (CRD). AIM: To determine whether peripheral NMDA-R are directly involved in CRD-mediated afferent nerve activity using an isolated colon-inferior splanchnic nerve preparation. METHODS: About 4 cm of distal colon and 1 cm proximal rectum with attached inferior mesenteric artery, ganglion and inferior splanchnic nerve branches were isolated and transferred into the main chamber of an organ bath. Unit action potentials were recorded from thin nerve filaments teased from inferior splanchnic branches or the mesentery nerve. CRD was provided hy a mini-latex balloon made from a piece of fatigued latex membrane that had a diameter of ~gmm when inflated with O.4ml air. The response of units to quick inflation and withdrawal of 0.3-0.5ml of air with raising and failing phases 0.5 sec and a 2g sec plateau was tested. Distensions were repeated at intervals not less than 4 min apart. Drugs were directly administered via the inferior mesenteric artery in a volume of 0.1 ml. RESULTS: Neither vehicle, nor the non-compstitive NMDA-R open channel blocker memantine (2g/~g) administered via intra-arterial injection had any effect on ongoing basal activity. However, memantine suppressed the responses of all units to subsequent CRD more than 65%. After intra-arterial washing, the responsiveness to CRO partially recovered (-50%) indicating that the effect of memantine was reveraihle. Intra-arterial injection of 10 p.g NMDA together with 5 p.g D-serine (a required co-agonist) in low Mg 2+ Ringers (to remove voltage-dependent inhibition) transiently increased spontaneous activity more than 3-fold over basal levels. Furthermore, prior treatment with a subthreshold dose of NMDA (5 ~g) in combination with D-serine enhanced CRD mediated responses >30%. Injection of D-serine alone in low Mg 2. Ringers had no effect of basal or evoked activity. CONCLUSIONS: These results strongly suggest that NMDA-R expressed on peripheral terminals of extrinsic primary afferents of the rat colon modulate, and may be directly involved, in mechanically induced nociception in this tissue. [Supported by NIH grants DK58173 and DK48476, and funds from AstraZeneca R&D, MOIndal]

Incomplete segregation of endorgan-specific vestibular ganglion cells in mice and rats

The endorgan-specific distribution of vestibular ganglion cells was studied in neonatal and postnatal rats and mice using indocarbocyanine dye (DiI) and dextran amines for retrograde and anterograde labeling. Retrograde DiI tracing from the anterior vertical canal labeled neurons scattered throughout the whole superior vestibular ganglion, with denser labeling at the dorsal and central regions. Horizontal canal neurons were scattered along the dorsoventral axis with more clustering toward the dorsal and ventral poles of this axis. Utricular ganglion cells occupied predominantly the central region of the superior vestibular ganglion. This utricular population overlapped with both the anterior vertical and horizontal canals' ganglion cells. Posterior vertical canal neurons were clustered in the posterior part of the inferior vestibular ganglion. The saccular neurons were distributed in the two parts of the vestibular ganglion, the superior and inferior ganglia. Within the inferior ganglion, the saccular neurons were clustered in the anterior part. In the superior ganglion, the saccular neurons were widely scattered throughout the whole ganglion with more numerous neurons at the posterior half. Small and large neurons were labeled from all endorgans. Examination of the fiber trajectory within the superior division of the vestibular nerve showed no clear lamination of the fibers innervating the different endorgans. These results demonstrate an overlapping pattern between the different populations within the superior ganglion, while in the inferior ganglion, the posterior canal and saccular neurons show tighter clustering but incomplete segregation. This distribution implies that the ganglion cells are assigned for their target during development in a stochastic rather than topographical fashion.

An anatomical study of the tympanic branch of the glossopharyngeal nerve (nerve of Jacobson)

Our study was aimed to examine the anatomic relationships of the tympanic branch of the glossopharyngeal nerve (GPN), namely the Jacobson's nerve (JN). The JN is the first branch of the GPN after having passed the jugular foramen. It contributes to the tympanic plexus on the promontory. It transmits secretory innervation to the parotid gland. Its possible role in the regulation of the middle ear pressure has also been hypothesized in terms of animal studies. Using microdissection techniques and high-resolution computed tomography (HRCT) scanning, the anatomic relationships and course of the JN were examined in eight formalin-preserved cadavers (16 sides). A morphometric analysis related to the JN was also performed both in the 16 cadavers and 40 dry-skull specimens. The JN emerged from the inferior ganglion of the GPN in all specimens. The mean distance between the ganglion and the genu of the GPN was 11.3 mm. The inferior 2/3 of the tympanic canal (TC) followed a vertical course, and then it ran anteromedially with an angle of 160 degrees to 170 degrees. The mean length of the TC was 9.5 mm. The TC was well-defined in all axial HRCT scans. In 2 cases the JN was entirely encased in a bony canal in the middle ear. A double JN was observed in one case. This study gives an additional information regarding the anatomy of the JN.

Trigeminal ganglion innervation of the cochlea—a retrograde transport study

Innervation patterns of sensory nerves from the trigeminal ganglion to the cochlear blood vessels were studied using retrograde transport of wheat germ agglutinin conjugated to horseradish peroxidase. Guinea-pigs ( n=7) were unilaterally implanted with an osmotic pump and a cannula for cochlear delivery of 2% or 20% wheat germ agglutinin–horseradish peroxidase (Group 1), 2% wheat germ agglutinin–horseradish peroxidase followed by 100 μmol capsaicin (Group 2), or vehicle alone. Histological sections of the trigeminal ganglia, the C1 and C2 dorsal ganglia, the superior and inferior ganglia of the glossopharyngeal nerve bilaterally, the midbrain and the brainstem were obtained after 48 h of infusion. In Group 1, a large number of labeled nerve cell bodies were observed in the anteromedial portion of the trigeminal ganglion and at the origin of the ophthalmic nerve. Some labeled cells were also found on the lateral side of the ophthalmic nerve, as well as on the medial side of the maxillary nerve root. Capsaicin pretreatment significantly reduced the density of labeled neurons in the trigeminal ganglion. A few labeled neurons were also found in the trigeminal brainstem nucleus complex and in certain auditory brainstem nuclei. No wheat germ agglutinin–horseradish peroxidase-positive cells were observed in the spinal C1 or C2 cervical ganglia or in the superior or inferior glossopharyngeal ganglia. In contrast, wheat germ agglutinin–horseradish peroxidase application to the middle ear resulted in labeled cells in the middle posterolateral portion of the trigeminal ganglia and in the superior ganglia of the glossopharyngeal nerve. These results provide the first direct evidence that the trigeminal ganglion sends projections to the cochlea.

Alterations of mouse embryonic branchial nerves and ganglia induced by ethanol.

An immunostaining technique using monoclonal antibodies to a neurofilament protein has allowed us to visualize defects in the development of cranial nerves and ganglia of 10 to 10.5 days mouse embryos following exposure to ethanol in whole embryo culture. Reference patterns for development of cranial nerves and ganglia of control mouse embryos explanted and examined when they had 25 to 34 pairs of somites were established. Additionally, control mouse embryos were grown in whole embryo culture for 48 h, with culture being initiated in embryos having 6 to 7 somite pairs. At the end of the culture period, only minor differences were observed between the control groups. An experimental group of embryos was cultured in the presence of increasing doses (1.6, 3.2, 4, and 4.8 g/l) of ethanol. Defects were observed in the development of the glossopharyngeal and vagus nerves. These abnormalities included absence of the dorsal root (superior ganglion) of IX, star-like shape of inferior ganglion IX, disorganization of the rootlets of nerve X and abnormal fibers between the two nerves and ganglia. These results suggest that the migration and patterning of neural crest cells derived from r6 and r7 may be particularly affected by ethanol. The results also demonstrate the usefulness of this approach in evaluating the susceptibility of the developing cranial nerves to toxicant exposure.

Projections of the individual vestibular end-organs in the brain stem of the squirrel monkey

The central nervous system (CNS) projections of primary afferent neurons from individual vestibular receptors were studied using horseradish peroxidase (HRP) or biocytin labeling in 14 ears from 7 adult squirrel monkeys using the technique developed in the chinchilla (Lee et al., 1989, 1992). The specificity of labeling was verified by examining the location of the labeled fibers and cell bodies in the vestibular nerve and Scarpa's ganglion. Labeled fibers and cells were restricted to nerves and areas belonging to groups of cells in either the superior or the inferior ganglion of the vestibular nerve. In the vestibular nerve root, labeled primary afferent fibers also exhibited a receptor-dependent segregation at the entrance to the medulla. Fibers from the HSC and the SSC were found rostrally and those from the PSC and the SAC were found in the caudal area. The UTR fibers were situated intermediate between these two groups of fibers. (A bundle of fibers, probably vestibular efferents, was identified immediately rostrally and ventromedially to the UTR fibers.) The primary afferent fibers bifurcated into secondary ascending and descending fibers at the lateral border of the vestibular nuclei, forming a longitudinal rostrocaudal vestibular tract. The secondary fibers from individual end-organs occupied specific locations in the tract: the UTR fibers were dorsal to the SSC and the HSC fibers, PSC fibers were found most medially, and the SAC fibers occupied the lateralmost area. The secondary UTR fibers overlapped considerably with those of the SSC and the HSC. The orderly receptor-dependent segregation of fibers was more prominent in the descending tracts than in the ascending tracts. In the vestibular nuclei complex the location of the tertiary branches of various end-organs exhibited considerable overlap within the major vestibular nuclei (SN, superior nucleus; LN, lateral nucleus; MN, medial nucleus; DN, descending nucleus). There were still differences, however, in the projection pattern. Fibers from the SAC ran primarily in the lateral area, fibers from the SSC and the UTR were found ventromedially to the SAC fibers, and the HSC projected slightly medially to the fibers from the SSC. The PSC fibers projected most medially. The UTR and SAC sent numerous fibers to the cerebellum. Fibers from the semicircular canals projected through the rostrodorsal region of the SN and presumably also projected to the cerebellum. The precise termination of fibers was evaluated by studying the location of labeled boutons, which were identified in all major vestibular nuclei. Labeled boutons from all the receptors were in the rostral and central areas of the SN, and in the MN mainly in the rostral two-thirds. In the LN, boutons from all the receptors were in the rostroventral part, most of which were from the UTR and SAC. No labeled boutons were in the caudodorsal part of this nucleus. Labeled boutons in the DN primarily surrounded the descending tract fibers and were particularly prominent medially. In specimens in which superior vestibular nerve receptor organs were scratched vestibular efferent fibers were also labeled. These fibers traveled in the most ventral part of the vestibular nerve root and projected in the ventral aspect of the LN to labeled soma in the ipsilateral and contralateral brain stem. Specificity the in projection patterns of efferent fibers from different end-organs could not be ascertained.