扩大经蝶窦入路颈内动脉海绵窦段显微镜、内镜下的解剖学研究

目的研究扩大经蝶窦入路颈内动脉海绵窦段的显微镜及内镜下的解剖特点。方法在10具动静脉灌注染料的成人新鲜尸头上模拟扩大经蝶窦手术入路，在显微镜及内镜下观察颈内动脉海绵窦段的走行特点，及颈内动脉海绵窦段与垂体的关系，测量双侧颈内动脉海绵窦段在不同水平的距离。结果颈内动脉海绵窦段分为5段，有3个动脉分支，其在蝶窦外侧壁上形成颈内动脉隆突，与视神经隆突形成视神经-颈动脉凹陷，是内镜手术中确定中线的标志。颈内动脉前曲段的内侧缘距垂体中线的距离为（11．94±1．90）mm（9．02～14．86mm），后曲段的内侧缘距垂体中线的平均距离为（7．96±2．07）mm（5．64～11．58mm）。结论颈内动脉海绵窦段是扩大经蝶窦手术入路中最重要的解剖结构。内镜下扩大经蝶窦手术可清晰显示海绵窦内的颈内动脉及其分支血管和神经等重要的组织结构，是处理由鞍内侵犯海绵窦内侧壁病变的良好手术方式。     

Anatomical and computed tomographic analysis of C1 vertebra

Craniovertebral junction surgery requires knowledge regarding the anatomy of this region, particularly the C1 vertebra. Both C1 laminectomy and C1-2 instrumentation necessitate preoperative information about bony landmarks and the vertebral artery. This study compares the results obtained from anatomic and computed tomographic measurements of C1 bony landmarks. 31 C1 cervical vertebrae were measured; the C1 AP diameter, and C1 transverse diameter, the facet diameter, the distance between the anterior tubercle and the anterior aspect of the C1 lateral mass on a lateral view, the distance between the midline and the vertebral artery groove on the outer cortex of the posterior arch of C1 anatomically and computed tomographically. Anatomic measurements were performed by an anatomist using a Vernier caliper accurate to 0.1 mm, whereas the computed tomographic measurements were performed by a radiologist on bone window computed tomography (CT). The mean values and the differences between two measurement modalities were analysed using a paired t-test. There was no statistical difference between the results obtained by anatomical and radiological measurements for six parameters. There was, however, a statistically significant difference between two modalities regarding the distance between the midline and vertebral artery groove on the outer cortex of posterior arch of C1, while slightly different, the difference is within 1 mm and, therefore, not clinically significant. It is concluded that CT reflects most anatomical details of bony landmarks of C1.     

Successful resection of anterior and anterolateral lesions at the craniovertebral junction using a simple posterolateral approach

Tumors at the craniovertebral junction (CVJ) often present a challenge due to proximity to vital neurovascular structures. In the last few decades, many authors have proposed complex surgical approaches to access pathologies located anterior or anterolateral to the CVJ with the hopes of reducing morbidity. We propose that the simple posterolateral approach in a semi-sitting position can be used to resect most anterior and anterolateral CVJ tumors safely and effectively. We retrospectively reviewed the clinical series of 10 patients treated by the senior author using the posterolateral suboccipital approach to treat anterior or anterolateral CVJ pathologies. We describe our surgical techniques, outcomes, and present illustrative patients. Gross total resection was achieved in eight patients (80%). Good functional outcome (Glasgow Outcome Scale 4–5) was obtained in all patients. Preoperative symptoms and deficits were improved (78%) or stable (22%) in all patients. There was one (10%) surgical complication that was cerebrospinal fluid leak requiring reoperation. There was no permanent morbidity or mortality in this series. There were two (20%) medical complications including deep vein thrombosis and pulmonary embolus. There were three (30%) transient neurologic complications, dysphagia in two and dysarthria in one, all of which resolved completely in early follow-up. The majority of anterior or anterolateral CVJ lesions can be successfully removed using the simple posterolateral approach.     

The unusual origin of the sternocleidomastoid artery from the lingual artery

The sternocleidomastoid (SCM) artery supplying blood to the SCM muscle has different origins according to its anatomical segment. The authors performed cadaveric neck dissection to review the surgical anatomy of neurovascular structures surrounding the carotid artery in the neck. During the dissection, an unusual finding was cited in which the SCM artery supplying the middle part of the SCM muscle originated from the lingual artery (LA); it was also noted that it crossed over the hypoglossal nerve (HN). There have been extremely rare reports citing the SCM artery originated from the LA. Though the elevation of the HN over the internal carotid artery was relatively high, the vascular loop crossing over the HN was very close to the carotid bifurcation. Special anatomical consideration is required to avoid the injury of the HN during carotid artery surgery.     

Importance of the perforating arteries in the proximal part of the PICA for surgical approaches to the brain stem and fourth ventricle - an anatomical study

Objective

The purpose of this study is to examine the perforating arteries (PAs) in the proximal part of the posterior inferior cerebellar artery (PICA) for surgical approaches to the brain stem and fourth ventricle, and to stress their importance in microsurgical procedures.

Methods

Twenty-six adult cadaver obtained from routine autopsies were used. During the examination, the PAs and the segmental structure of the proximal part of the PICAs and their relation to the neighbouring anatomical structures were demonstrated.

Results

We classified the PICAs into 4 types on the basis of the distance of the middle point of the width of the caudal loop to the midline, and their presence or absence as Group A (symmetrical, anterior medullary type: 26.9%), Group B (lateral medullary type: 15.4%), Group C (asymmetrical type: 38.5%), and Group D (unilateral type: 19.2%). The number of the PAs in the tonsillomedullary segment and the caudal loop was higher than those originating from the other segments.

Conclusions

Approaches to the medial or lateral of the PICA should be made in a way that protects the PAs (avoiding retraction of the PICA). Otherwise the PAs will be damaged and as a result brain stem ischaemia may occur, which can have serious clinical outcomes.     

Autoradiographic localization of newly synthesized octopamine to retinal efferents in the Limulus visual system

The biogenic amine octopamine is synthesized from both tyrosine and tyramine in the lateral, median, and ventral eyes of Limulus. The autoradiographic studies presented here were designed to locate the sites of octopamine synthesis in the ventral and lateral eyes. We found that efferent fibers, which project to ventral and lateral eyes from the central nervous system, became intensely and selectively labeled during in vitro incubations with 3H-tyramine. In the ventral eye, more than 95% of the efferent fibers were labeled. Results of biochemical analyses suggested that most of the radioactive substance within these efferent fibers was newly synthesized octopamine. The selective labeling of efferent fibers during incubation with 3H-tyramine was used as an anatomical tool to study the number and distribution of efferent fibers within the ventral eye. Light microscopic (LM) reconstructions of the distribution of label in serial longitudinal sections through ventral optic nerves together with electron microscopic (EM) autoradiographic analyses revealed between 70 and 200 efferent axons. The results of these studies and of reconstructions of efferent innervation to photoreceptor somata suggest that each ventral photoreceptor cell or each small cluster of cells is innervated by a separate efferent fiber. Both LM reconstructions and EM analyses showed that efferent fibers ramify extensively and specifically in and near the internal rhabdom of ventral photoreceptor cells. In EM autoradiographs of lateral eyes incubated with 3H- tyramine, the silver grains that were located over ommatidia were concentrated exclusively over efferent fibers. All of these efferent fibers, which lay near rhabdoms and in partitions between retinular cells, were labeled. The results of our present studies support our hypothesis that octopamine is a neurotransmitter in Limulus retinal efferent fibers. This amine may modulate the biochemistry and physiology of ventral photoreceptor cells and may mediate many of the known effects of circadian efferent innervation to the lateral eye.     

Projections of the nucleus lentiformis mesencephali in pigeons (Columba livia): a comparison of the morphology and distribution of neurons with different efferent projections

The avian nucleus lentiformis mesencephali (LM) is a visual structure involved in the optokinetic response. The LM consists of several morphologically distinct cell types. In the present study we sought to determine if different cell types had differential projections. Using retrograde tracers, we examined the morphology and distribution of LM neurons projecting to the vestibulocerebellum (VbC), inferior olive (IO), dorsal thalamus, nucleus of the basal optic root (nBOR), and midline mesencephalon. From injections into the latter two structures, small LM cells were labeled. More were localized to the lateral LM as opposed to medial LM. From injections into the dorsal thalamus, small neurons were found throughout LM. From injections into the VbC, large multipolar cells were found throughout LM. From injections into IO, a strip of medium-sized fusiform neurons along the border of the medial and lateral subnuclei was labeled. To investigate if neurons project to multiple targets we used fluorescent retrograde tracers. After injections into IO and VbC, double-labeled neurons were not observed in LM. Likewise, after injections into nBOR and IO, double-labeled neurons were not observed. Finally, we processed sections through LM for glutamic acid decarboxylase (GAD). Small neurons, mostly in the lateral LM, were labeled, suggesting that projections from LM to nBOR and midline mesencephalon are GABAergic. We conclude that two efferents of LM, VbC and IO, receive input from morphologically distinct neurons: large multipolar and medium-sized fusiform neurons, respectively. The dorsal thalamus, nBOR, and midline mesencephalon receive input from small neurons, some of which are likely GABAergic.     

Topographic organization and neurochemical identity of dorsal raphe neurons that project to the trigeminal somatosensory pathway in the rat.

The primary goals of this study were to: 1) examine the distribution of neurons within the dorsal raphe (DR) nucleus that project to cortical and subcortical sites along the trigeminal somatosensory pathway in rat; 2) determine the extent to which different regions within this ascending sensory system receive collateral projections from the same DR neuron; and 3) identify the putative transmitters contained within these DR projection neurons. Long-Evans hooded rats received pressure injections of various combinations of retrograde fluorescent tracers; into the whisker-related regions of the primary somatosensory cortex (barrel field cortex [BC]), ventral posterior medial thalamus (VPM), and principal nucleus of the trigeminal complex (PrV). The distribution of retrogradely labeled neurons within the DR was examined by fluorescence microscopy. The major finding was that cortically projecting neurons were located within the midline regions of the rostral portion of the DR, whereas cells projecting to subcortical trigeminal somatosensory structures were distributed bilaterally in the lateral wing regions of the DR as well as in the midline portions of the nucleus. Single neurons that send axon collaterals to multiple cortical and subcortical trigeminal somatosensory targets were observed in the dorsomedian and ventromedian regions of the DR. DR neurons that projected to cortical and subcortical sites contained serotonin but not tyrosine hydroxylase, the marker enzyme for catecholamine transmitters. Taken together, these findings provide further evidence of neurochemical specificity and functional anatomical organization within the DR efferent projection system.     

Localization of the spinal accessory motoneurons in the cervical cord in connection with the phrenic nucleus: an HRP study in cats

The localization of the spinal accessory motoneurons (SAMNs) that innervate the accessory respiratory muscles, the sternocleidomastoid (SCM) and trapezius (TP) muscles, was identified in the cat using the horseradish peroxidase (HRP) method. In the cases of HRP bathing of the transected spinal accessory nerve (SAN), HRP-labeled motoneurons were observed ipsilaterally from the C1 to the rostral C6 segments of the spinal cord. Labeled neurons were located principally in the medial and central regions of the dorsomedial cell column of the ventral horn in the C1 segment, in the lateral region of the ventrolateral cell column in the C2-C4 segments, between the ventrolateral and ventromedial cell columns in the C5 segment and in the lateral region of the ventromedial cell column in the C6 segment. In the cases of HRP injection into either SCM or TP muscles, labeled SCM motoneurons were found in the C1-C3 segments of the spinal cord and labeled TP motoneurons were chiefly localized more caudally within the spinal accessory nucleus. The present study revealed that, in the C5 and C6 segments, the SAMNs have a very similar topographic localization to the phrenic nucleus in the ventral horn. This finding implicated the functional linkage of the SAMNs with the phrenic motoneurons in particular types of respiration.     

Spinocerebellar projections from the central cervical nucleus in the cat, as studied by anterograde transport of wheat germ agglutinin-horseradish peroxidase

The projection of the spinocerebellar tract arising from the central cervical nucleus with crossed ascending axons was studied by the anterograde transport of wheat germ agglutinin conjugated to horseradish peroxidase (WGA-HRP) in the cat. Following injections of WGA-HRP into the C1 to the C4 or C5 segments, labeled terminals were seen in lobules I-VI, sublobule VIIb, lobules VIII and IX, the paramedian lobule, crus I and crus II, and the simple lobule. About 67-80% of the total number of labeled terminals were in the anterior lobe and 20-33% in the posterior lobe; the labeled terminals were abundant in lobules I (11-20%), II (11-28%), III (5.7-9.6%), IV (8.6-15.4%), and VIII (9-12%). The labeled terminals were densely distributed in the basal half or basal two-thirds of sublobules IIa-Va and VIf-VIb in their apicobasal extent and the transitional areas between neighboring sublobules. In sublobules Ia, Ib, and Vg they were distributed over the entire sublobule. The labeled terminals were most abundant within 0.5 mm of the midline (30-55% of the total number in each sublobule). Results in cases with injections into the C2-C4 segments, preceded by hemisection between the C1 and C2 segments, revealed that the projections were bilateral but predominantly contralateral to the cells of origin; the proportion of the quantity of the contralateral projection to that of the ipsilateral was about 60:40% in sublobules Ia-Vb and sublobules Ve-Vg. The projection field in the horizontal plane of the lobule was reconstructed from a series of cross sections through each sublobule. The labeled terminals were distributed in three major longitudinal areas named areas 1, 2, and 3, respectively. These areas were confined in the basal half to two-thirds of lobules III-V: area 1 located in zone A1 of Voogd (within 0.25 mm of the midline); area 2 located in zones A1 to A2 (at around 0.5 mm lateral to the midline); and area 3 located in the lateral part of zone A2 to zone B (between 0.75 mm and 1.5 mm lateral to the midline in lobule III, and between 1.0 mm and 2.0 mm lateral to the midline in lobules IV-VI). An indefinite area 4 appeared in zones B and C of some lobules. In sublobules Ia, Ib, Vf, and Vg the three areas extended throughout the apicobasal length.(ABSTRACT TRUNCATED AT 400 WORDS)     

Reorganization of cerebral control of tactile placing after interrupting a spinal ascending system in cats with pyramid section

Interruption of a spinal ascending system by hemisection of the spinal cord at mid-thoracic level restores the tactile placing (TP) which is lost after bulbar pyramid section in cats. To determine the location of the ascending system in the spinal cord, partial lesions involving various dorsal, lateral, or ventral tracts were made at mid-thoracic level in cats with pyramid section. To determine the supraspinal control of the recovered TP after pyramid section and spinal cord hemisection, lesions were made in other cortical and subcortical structures essential to TP and also in cortical areas which are not normally involved in TP in cats with recovered TP. The findings demonstrate that the spinal ascending system is located in the ventral part of the lateral funiculus and that the cerebral association cortex takes over the function of motor cortex in the reorganized control of TP. A slow course of TP recovery along with no recovery of impaired distal forelimb movements resulting from pyramidotomy were also observed.     

Cerebellar pathways to ventral midbrain and nigra

This study on cat and rat indicates that the cerebellar nuclei connect with a continuum of cells located on either side of midline in the ventral tegmentum of the midbrain. The following nuclei are located within this region: nigra, ruber, interpeduncularis, ventral tegmental (Tsai), and linearis rostralis. The nucleus fastigii projection is primarily ipsilateral to this region by way of a mediaal and dorsal pathway (accessory brachium conjunctivum). A greater number of these fibers terminates in medial as contrasted to lateral structures. The projections of nuclei interpositus-dentatus are primarily contralateral and become part of a lateral and ventral pathway through the brachium conjunctivum. Reduced-silver methods and horseradish peroxidase-treated materials furnish some evidence for a small Purkinje cell connection directly to the ventral tegmental area. Biochemical studies on dopamine levels in the forebrain indicate there is an increase ipsilateral to the cerebellar cortical lesion whereas a lesion in nucleus fastigii results in a decrease of dopamine levels in ipsilateral forebrain. Some cerebellar influences on catecholamine systems are discussed.     

Efferent projections of reuniens and rhomboid nuclei of the thalamus in the rat

The nucleus reuniens (RE) is the largest of the midline nuclei of the thalamus and exerts strong excitatory actions on the hippocampus and medial prefrontal cortex. Although RE projections to the hippocampus have been well documented, no study using modern tracers has examined the totality of RE projections. With the anterograde anatomical tracer Phaseolus vulgaris leuccoagglutinin, we examined the efferent projections of RE as well as those of the rhomboid nucleus (RH) located dorsal to RE. Control injections were made in the central medial nucleus (CEM) of the thalamus. We showed that the output of RE is almost entirely directed to the hippocampus and "limbic" cortical structures. Specifically, RE projects strongly to the medial frontal polar, anterior piriform, medial and ventral orbital, anterior cingulate, prelimbic, infralimbic, insular, perirhinal, and entorhinal cortices as well as to CA1, dorsal and ventral subiculum, and parasubiculum of the hippocampus. RH distributes more widely than RE, that is, to several RE targets but also significantly to regions of motor, somatosensory, posterior parietal, retrosplenial, temporal, and occipital cortices; to nucleus accumbens; and to the basolateral nucleus of amygdala. The ventral midline thalamus is positioned to exert significant control over fairly widespread regions of the cortex (limbic, sensory, motor), hippocampus, dorsal and ventral striatum, and basal nuclei of the amygdala, possibly to coordinate limbic and sensorimotor functions. We suggest that RE/RH may represent an important conduit in the exchange of information between subcortical-cortical and cortical-cortical limbic structures potentially involved in the selection of appropriate responses to specific and changing sets of environmental conditions.     

枕大孔区肿瘤的分型及手术入路选择

目的 探讨枕大孔区肿瘤的分型及手术入路.方法 回顾性分析显微手术治疗的43例枕骨大孔区肿瘤,根据肿瘤位置分为:Ⅰ型(背侧)和Ⅱ型(腹侧),Ⅰ型又分为Ⅰ a(髓外)、Ⅰ b(髓内)、Ⅰ c(髓内外)三型,Ⅱ型又分为Ⅱa(髓外)和Ⅱb(髓内)两型.对于17例Ⅰ型患者选择后正中入路,26例Ⅱ型患者选择远外侧入路.结果 全切肿瘤35例(81%),无手术死亡,随访期内无肿瘤复发.临床症状改善32例;保持原有症状3例;加重8例,包括出现新的脑神经症状、肢体运动障碍和呼吸困难.结论 枕大孔区肿瘤的术前分型有助于手术入路的选择和判断手术效果,Ⅰ型多选择后正中入路,Ⅱ型选择远外侧入路.

Abstract：

Objective To explore the classification and surgical approach of magnum foramen tumor.Method A retrospective analysis was performed for 43 surgically treated patients with tumors involving the foramen magnum.According to the site of the tumor,the classification was divided to:Type Ⅰ ,located at dorsal, Ⅰ a extra - medullary, Ⅰ b intra - medullary, Ⅰ cintra - and extramedullary; Type Ⅱ,located at ventral, Ⅱ a extramedullary, Ⅱ b intramedullary.The midline approach was used in the Type Ⅰ (17cases), while the lateral or far- lateral approach for the Type Ⅱ (26 cases).Results Total excision was performed in 35(81% ).There were no mortality and no recurrence during the follow -up period.Thirtytwo patients had improvement in their neurological status, 3 cases unchanged.There were 8 cases aggravation,including newly cranial nerve deficits, hemiplegia, dyspnoea.Conclusions The preoperative classification was useful for the selection of surgical approach and evaluation of surgical outcome.The midline approach was apt to Type Ⅰ , while the lateral or far - lateral approach for the Type Ⅱ.     

Zonal organization of climbing fiber projections to the uvula in the cat

Climbing fiber projections from the inferior olive to the uvula of the cerebellum were studied in the cat by using retrograde axonal transport of horseradish peroxidase. Following large and small injections into various parts of the uvula, the distribution of labeled cells in the inferior olive was investigated. The findings indicate six longitudinal zones extending throughout the dorsal and ventral uvula: the caudal part of the nucleus beta projects to a most medially located zone (caudal beta zone) with a width of about 0.4 mm; the rostral part of the nucleus beta projects to a zone located at about 0.6 mm from the midline (rostral beta zone); the caudal part of the medial accessory olive (MAO) projects to a zone (caudal MAO zone) located lateral to the rostral beta zone; the dorsomedial cell column projects to a zone (dorsomedial cell column zone) located in the intermediate part of the uvula at about 1.2 mm from the lateral edge of the uvula; the ventral lamella of the principal olive (PO) projects to a zone (ventral lamella of PO zone) about 0.7 mm from the lateral edge of the uvula; finally, the rostral part of the MAO projects to the most lateral zone (rostral MAO zone). These conclusions are in general agreement with those of earlier studies and also provide a more detailed zonal configuration of climbing fiber projections to the uvula.     

Microsurgical anatomy of the ophthalmic artery and the distal dural ring for the juxta-dural ring aneurysms via the pterional approach.

Microsurgical anatomy for the pterional approach was studied regarding the origin and the course of the ophthalmic artery and the distal dural ring using human cadaveric specimens, with special reference to the surrounding bony structures. In 50 human adult formalin-fixed cadaveric cerebral hemispheres and 10 block specimens of the skull base region including the ophthalmic artery and the carotid dural ring were examined under magnification using an operating microscope. The ophthalmic artery originated from the intradural portion of the internal carotid artery (ICA), except in 5% where the ophthalmic artery originated extradurally. The extradural origin had two patterns: one was that the ophthalmic artery penetrated the bony optic strut (trans-optic strut pattern) and the other was that it coursed into the optic canal proximally to the optic strut without bone penetration (supra-optic strut pattern). The origin of the intradural ophthalmic artery was commonly located at the medial third of the superior wall of the ICA (78%). The ophthalmic artery was commonly taking an S-shaped course in the intradural portion and entered the optic canal over the optic strut. The distal dural ring was tightly adherent to the internal carotid artery; circumferential sectioning of the dural ring is required to mobilize the internal carotid artery. When approaching juxtadural ring ICA aneurysms via the pterional route, it is important to recognize the extradural origin, especially the trans-optic strut type, and to precisely understand the microsurgical anatomy around the dural ring.     

Atlantoaxial stabilization utilizing atlas translaminar fixation

Atlantoaxial instability is a potentially devastating sequela of tumor invasion to the upper cervical spine. We aim to report an alternative technique for atlantoaxial stabilization. Stabilization is technically demanding due to limited bony elements and proximity of the regional neurovascular structures. While the C1 lateral masses are considered robust points of fixation, one or both of these structures may be destroyed by pathology. A 54-year-old female presented with a lytic, metastatic lesion to one of the C1 lateral masses, which precluded its use for fixation. We utilized the contralateral hemilamina of the atlas for screw fixation and devised a stable construct that provided immediate stability. Thus, atlas translaminar fixation is a feasible option when the lateral masses cannot be utilized.     

Location of motoneurones projecting to the cat distal forelimb. II. Median and ulnar motornuclei

The position of the motornuclei projecting through the median (Mn) and ulnar (Ul) nerves to the cat distal forelimb has been investigated. Horseradish peroxidase (HRP) and fluorescent (Fl) compounds have been used as retrograde tracers. They were either injected into forelimb muscles or applied to the proximal end of transected forelimb nerves. Limb muscles that were not investigated were carefully denervated. The position and the architecture of the individual motornuclei were traced with HRP. The topographical relations between the nuclei were established with application of up to three different Fl compounds in the same animal. The Mn motoneurones had a bimodal distribution in the brachial spinal cord. The motoneurones to the pronator teres and flexor carpi radialis muscles were located in C7 and the other Mn motoneurones were located in C8 and Th1. In C7 the Mn motoneurones occupied a single representation area, which is located some distance medially of the lateral funiculus. In C8 and Th1 two Mn representation areas were found: A dorsal one that contacts the lateral funiculus and is located at the level of the central canal; a ventral one that is located ventrally in the ventral horn. The dorsal area is occupied by the motornuclei projecting to the intrinsic hand muscles and the ventral one by the nuclei projecting to the limb. The Ul motoneurones extend with an unimodal distribution from the caudal C7 to the caudal Th1 segments. They occupy a single, broad representation area. The dorsal part, which contacts the lateral funiculus, is located at the level of the central canal and harbours the nuclei to the intrinsic hand muscles. The other Ul nuclei are located ventromedially deep in the ventral horn. These results, together with those from the companion paper on the location of the deep radial motornuclei, provide important anatomical information for the investigation of the cat brachial enlargement.     

Postnatal phenotype and localization of spinal cord V1 derived interneurons

Developmental studies identified four classes (V0, V1, V2, V3) of embryonic interneurons in the ventral spinal cord. Very little is known, however, about their adult phenotypes. Therefore, we characterized the location, neurotransmitter phenotype, calcium-buffering protein expression, and axon distributions of V1-derived neurons in the adult mouse spinal cord. In the mature (P20 and older) spinal cord, most V1-derived neurons are located in lateral LVII and in LIX, few in medial LVII, and none in LVIII. Approximately 40% express calbindin and/or parvalbumin, while few express calretinin. Of seven groups of ventral interneurons identified according to calcium-buffering protein expression, two groups (1 and 4) correspond with V1-derived neurons. Group 1 are Renshaw cells and intensely express calbindin and coexpress parvalbumin and calretinin. They represent 9% of the V1 population. Group 4 express only parvalbumin and represent 27% of V1-derived neurons. V1-derived Group 4 neurons receive contacts from primary sensory afferents and are therefore proprioceptive interneurons. The most ventral neurons in this group receive convergent calbindin-IR Renshaw cell inputs. This subgroup resembles Ia inhibitory interneurons (IaINs) and represents 13% of V1-derived neurons. Adult V1-interneuron axons target LIX and LVII and some enter the deep dorsal horn. V1 axons do not cross the midline. V1-derived axonal varicosities were mostly (>80%) glycinergic and a third were GABAergic. None were glutamatergic or cholinergic. In summary, V1 interneurons develop into ipsilaterally projecting, inhibitory interneurons that include Renshaw cells, Ia inhibitory interneurons, and other unidentified proprioceptive interneurons.     

Zonal organization of olivocerebellar projections to the uvula in rabbits

Olivocerebellar projections to the uvula were studied by means of retrograde axonal transport of horseradish peroxidase (HRP) in pigmented rabbits. The distribution pattern of labeled cells in the inferior olive was compared among cases following large- and microinjections of HRP into the uvula. Findings indicate topographically organized projections to longitudinally oriented zones. There are at least 6 zones in the rabbit's uvula. The caudal part of the nucleus beta projects contralaterally to a most medially located zone (caudal beta zone). The rostral part of the nucleus beta projects to a little more laterally located zone (rostral beta zone) at a distance of about 1 mm from the midline of the uvula. The caudolateral part of the MAO projects to a zone (caudolateral MAO zone) located laterally to the rostral beta zone. The dorsomedial cell column projects to a zone (dorsomedial cell column zone) located in the intermediate part of the uvula at about 2 mm from the midline. The rostrolateral part of the MAO projects to the most lateral zone (rostrolateral MAO zone) of the uvula. Finally, the ventral lamella of the PO projects to a zone (ventral lamella of PO zone) located between the rostrolateral MAO zone and the dorsomedial cell column zone.