Location of the phrenic nucleus in the human spinal cord

Eight normal human spinal cords were studied. Spinal segments were identified and embedded in paraffin wax. Serial cross sections were cut at 25 μm and stained by cresyl violet. Motor columns were reconstructed adapting Elliott's (1942) methods. Motor columns were classified into the medial and lateral divisions and were numbered sequentially from medial to lateral at the level of Cl. In the cervical cord, 8 motor columns were traced. Column 1, corresponding to the medial column, presented 3 subdivisions designated as 1a, 1b and 1c with ventral, dorsal and lateral positions respectively. Columns 1a and 1b extended throughout the cervical region while 1c was confined to 3rd, 4th and 5th cervical segments. At the level of C3, 1c was a discrete column situated lateral to 1a and 1b but at C4 and C5 it became displaced medially close to the medial margin of the ventral horn. In cross section, it presented smaller medial and large lateral part. With the help of clinical and developmental evidence an attempt was made to correlate column 1c with the phrenic nucleus.     

Termination patterns of calcitonin gene-related peptide-immunoreactive nerve fibers in the dorsal horn of the human spinal cord

Summary CGRP-immunoreactive varicose nerve fibers displayed three kinds of termination patterns in the cervical, thoracic and lumbar segments of the human spinal cord. Bundles of immunoreactive fibers formed a loose network in lamina I. A homogenous band of immunoreactive fibers filled lamina II. Multiple bundles of CGRP-positive fibers coursed through the superficial laminae towards deep portions of the grey matter. In the lumbar segments, in contrast to the cervical and thoracic segments, the bundles could be followed deep into the dorsal funiculus. Bundles of varicose immunoreactive fibers were seen to twine around the dendrites of neurons located in lamina I, in the dorsal funiculus of the lumbar segments and deep in the dorsal horn (laminae III–V). The corresponding types of large and medium-sized neurons were found in silver impregnated adjacent spinal cord sections. It is suggested that neurons in the above locations preferentially receive multiple contacts from CGRP-containing nerve fibers along their extensive dendritic arborizations (CGRP-target neurons).     

Localization of the spinal nucleus of accessory nerve in rat: a horseradish peroxidase study

The spinal nucleus of the accessory nerve (SNA) comprises the group of somata (perikarya) of motor neurons that supply the sternocleidomastoid and trapezius muscles. There are many conflicting views regarding the longitudinal extent and topography of the SNA, even in the same species, and these disagreements prompted the present investigation. Thirty Sprague-Dawley rats (15 males, 15 females) were used. The SNA was localized by retrograde axonal transport of horseradish peroxidase. Longitudinally, the SNA was found to be located in the caudal part (caudal 0.9-1.2 mm) of the medulla oblongata, the whole lengths of cervical spinal cord segments C1, C2, C3, C4, C5 and rostral fourth of C6. In the caudal part of the medulla oblongata, the SNA was represented by a group of perikarya of motor neurons lying immediately ventrolateral to the pyramidal fibres that were passing dorsolaterally after their decussation. In the spinal cord, the motor neuronal somata of the SNA were located in the dorsomedial and central columns at C1, in the dorsomedial, central and ventrolateral columns at C2 and in the ventrolateral column only at C3, C4, C5 and rostral quarter of C6. The perikarya of motor neurons supplying the sternocleidomastoid were located in the caudal part (caudal 0.9-1.2 mm) of the medulla oblongata ventrolateral to the pyramidal fibres that were passing dorsolaterally after their decussation. They were also located in the dorsomedial and central columns at C1, in the dorsomedial, central and ventrolateral columns at C2 and only in the ventrolateral column at the rostral three-quarters of C3. The perikarya of motor neurons supplying the trapezius muscle were located in the ventrolateral column only in the caudal three-quarters of C2, the whole lengths of C3, C4 and C5, and in the rostral quarter of C6.     

芳香化酶在成年小鼠脊髓的表达

目的:探讨芳香化酶在正常成年小鼠脊髓组织中的表达特征。方法:取成年C57SJL小鼠,应用免疫组织化学、免疫荧光、免疫印迹检测正常雄性与雌性成年小鼠脊髓组织芳香化酶的分布特征。结果:芳香化酶在正常成年小鼠脊髓组织中的颈、胸、腰段均有表达,主要在灰质神经元中表达,尤其是第Ⅳ、Ⅴ、Ⅶ、Ⅸ层。脊髓腰段前角芳香化酶阳性运动神经元数量在雌雄间无明显的差异。结论:正常成年小鼠脊髓组织表达芳香化酶,不仅在后角感觉神经元中,前角运动神经元也确有表达,且其分布特征在雌雄间无明显差异。     

Effects of pathogenic action of botulinus toxin of spinal motoneurons of various types

Motoneurons of the lumbosacral region of the spinal cord were studied during local botulinus paralysis. The development of paralysis of the poisoned limb was accompanied by lowering of the membrane potential, the amplitude of the antidromic action potentials and of mono- and polysynaptic EPSPs, and the input resistance, and by an increase in the critical depolarization level of the soma membrane of phasic motoneurons in the affected segments of the spinal cord. The excitability of the tonic motoneurons was substantially unchanged in the course of development of local botulism.A. A. Bogomolets Department of Pathological Physiology, Saratov Medical Institute. (Presented by Academician of the Academy of Medical Sciences of the USSR P. N. Veselkin.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 80, No. 11, pp. 21–24, November, 1975.     

The central canal of the human spinal cord: a computerised 3-D study

Knowledge of the structure and function of the central canal of the human spinal cord is important in understanding the pathogenesis of syringomyelia. Analysis of the morphology of the central canal is difficult using isolated histological sections. A 3-dimensional reconstruction technique using digitised histological sections was therefore developed to visualise the morphology of the central canal. The technique was used to study the canal in the conus medullaris and filum terminale of 1 sheep and 4 human spinal cords. A variety of morphological features were demonstrated including canal duplication, a terminal ventricle and openings from the canal lumen into the subarachnoid space. The findings suggest the possibility of a functionally important fluid communication in the caudal spinal cord which may have a sink function.     

Duration of action potentials of motor units after spinal cord trauma

The duration of action potentials of motor units (MU) of the gastrocnemius and tibialis muscles was studied in patients with spinal cord trauma by the method of local electromyography. The duration of action potentials of gastrocnemius MU was found to be reduced on average by 27%, and of tibialis MU by 38% of the age norm. The degree of shortening of the action potentials of the gastrocnemius and tibialis MU was not directly dependent on the level of spinal cord injury, the length of time after trauma, or the severity of the spastic syndrome. Changes in the duration of action potentials of MU are evidently due to differences in the degree of atrophy developing as a result of prolonged adynamia.Department of Spinal Cord Trauma, A. V. Vishnevskii Institute of Surgery, Academy of Medical Sciences of the USSR, Moscow. (Presented by Academician of the Academy of Medical Sciences of the USSR M. I. Kuzin.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 86, No. 9, pp. 267–270, September, 1978.     

Glia to neuron ratio in the posterior aspect of the human spinal cord at thoracic segments relevant to spinal cord stimulation

Spinal cord stimulation (SCS) applied between T8 and T11 segments has been shown to be effective for the treatment of chronic pain of the lower back and limbs. However, the mechanism of the analgesic effect at these medullary levels remains unclear. Numerous studies relate glial cells with development and maintenance of chronic neuropathic pain. Glial cells are electrically excitable, which makes them a potential therapeutic target using SCS. The aim of this study is to report glia to neuron ratio in thoracic segments relevant to SCS, as well as to characterize the glia cell population at these levels. Dissections from gray and white matter of posterior spinal cord segments (T8, T9, intersection T9/T10, T10 and T11) were obtained from 11 human cadavers for histological analyses. Neuronal bodies and glial cells (microglia, astrocytes and oligodendrocytes) were immunostained, microphotographed and counted using image analysis software. Statistical analyses were carried out to establish significant differences of neuronal and glial populations among the selected segments, between the glial cells in a segment, and glial cells in white and gray matter. Results show that glia to neuron ratio in the posterior gray matter of the human spinal cord within the T8–T11 vertebral region is in the range 11 : 1 to 13 : 1, although not significantly different among vertebral segments. Glia cells are more abundant in gray matter than in white matter, whereas astrocytes and oligodendrocytes are more abundant than microglia (40 : 40 : 20). Interestingly, the population of oligodendrocytes in the T9/T10 intersection is significantly larger than in any other segment. In conclusion, glial cells are the predominant bodies in the posterior gray and white matter of the T8–T11 segments of the human spinal cord. Given the crucial role of glial cells in the development and maintenance of neuropathic pain, and their electrophysiological characteristics, anatomical determination of the ratio of different cell populations in spinal segments commonly exposed to SCS is fundamental to understand fully the biological effects observed with this therapy.     

经椎弓根椎体截骨术治疗脊柱后凸畸形的临床疗效观察

目的：探讨经椎弓根椎体截骨脊柱缩短术治疗并发脊髓神经功能障碍的脊柱后凸畸形的临床疗效。方法将2013年5月至2014年6月期间我院收治的80例并发脊髓神经功能障碍的脊柱后凸畸形患者纳入研究对象,采用随机数字表法分为观察组和对照组各40例,观察组患者接受经椎弓根椎体截骨术治疗,对照组患者接受经椎板和小关节突截骨术,比较2组患者手术情况、椎体愈合和神经功能恢复、治疗效果。结果观察组患者手术时间[(76.52±9.1) min]、术后下床活动时间[(3.28±0.43) d]短于对照组[(113.46±13.44) min,(5.67±0.68) d],术中出血量[(36.14±4.28) mL]、术后引流量[(17.92±2.12) mL]少于对照组[(55.23±7.15) mL,(29.64±4.28) mL]。观察组患者的Cobb角、出现初始尿意和强烈尿意时的膀胱容量[(6.12±0.68) mL,(456.56±51.78) mL]、残余尿量[(241.45±28.56) mL,(63.78±7.24) mL]低于对照组[(9.78±1.21) mL,(335.54±36.86) mL,(586.35±63.12) mL,(96.32±10.22) mL],椎间隙高度[(12.62±2.81) mL]高于对照组[(8.41±1.32) mm]。观察组治疗优良率(97.50%)明显高于对照组(82.50%)。结论经椎弓根椎体截骨脊柱缩短术治疗有助于减小手术创伤,促进术后恢复,纠正后凸畸形,改善神经功能,提高治疗效果。     

Nontumor lesions of spinal cord and spine

Nontumor lesions of the spinal cord and spine include developmental disorders, cystic tumor-like lesions, vascular disorders, infective diseases, demyelinating diseases, degenerative diseases, metabolic and toxic disorders, and spinal cord injury. In addition, diseases of the spine and extradural spaces secondarily cause spinal cord injury. Aside from tumors, these include developmental abnormalities, inflammatory diseases, nontumor space-occupying lesions, and tumor-like lesions such as lipomas, vascular malformations, and cysts. Awareness is required of hemostatic agents used during surgery and subsequently presenting as space-occupying lesions, which have to be differentiated from recurrent lesions. On the therapeutic front, stem cell transplantation into spinal cord for treatment of neurodegenerative disorders, spinal cord injury, and multiple sclerosis is a challenging prospect.     

Wiring diagrams of functional connectivity in monosynaptic reflex arcs of the spinal cord

The direct functional connections between Ia and group II spindle afferent fibers from the cat medial gastrocnemius muscle and their homonymous motoneurons were examined in 10 acute experiments. Trains of stretch-evoked impulses from as many as 20 undivided sensory fibers were recorded simultaneously from 5 dorsal root filaments, as well as the corresponding excitatory postsynaptic potentials (EPSPs) they elicited in 10-20 motoneurons. Spike-triggered averaging [13] of these tape-recorded signals revealed the functional connections (or non-connections) between each Ia or group II afferent fiber and each motoneuron. Wiring diagrams constructed from these data indicate that the probability of a functional connection between an afferent fiber and a motoneuron decreases with the size of either and with the distance between the entry point of the afferent fiber and the motoneuron.     

牛脊髓前角匀浆皮下注射损伤豚鼠脊髓运动神经元

目的探讨牛脊髓前角匀浆对豚鼠脊髓、前根及坐骨神经的影响。方法采用新鲜牛脊髓前角匀浆免疫豚鼠。观察脊髓、前根、坐骨神经光镜及超微结构的变化。结果豚鼠体重在第4次免疫后明显下降。脊髓前角运动神经元变性和丢失,有卫星、噬节及墓穴现象形成。电镜下最主要的表现是线粒体异常;其次神经元核周质内异常神经丝聚集,形成包涵体;轴突内异常神经丝聚集形成轴索球。前根及坐骨神经的变化,表现为轴索变性及继发的髓鞘改变。结论牛脊髓前角匀浆可以作为抗原引起豚鼠脊髓、前根及坐骨神经免疫所介导的损伤,为进一步研究运动神经元病的发病机制提供了可靠的方法。     

大鼠脊髓全横断后神经营养素-3在红核表达的变化

目的:研究大鼠脊髓全横断后神经营养素-3(NT-3)在红核表达的变化,为进一步探索脊髓损伤后的再生修复机制和神经营养因子治疗脊髓损伤提供实验依据。方法:雄性SD大鼠36只随机分为3组,脊髓横断组:大鼠脊髓在胸10~11节段之间完全横断,按存活时间不同又分为术后1、3、7及14d组;假手术组(只行椎板切除术);正常对照组。动物到达存活时间点后,应用免疫组织化学ABC法和图像分析技术检测NT-3在红核的表达。结果:对照组和实验组红核有NT-3阳性细胞。脊髓全横断后红核NT-3的表达逐渐增高,于术后7d达高峰,后缓慢下降。结论:脊髓全横断后红核对NT-3的表达增加,内源性NT-3的增加可能有利于受损的红核内神经元的存活与再生。     

Mu opioid receptors in developing human spinal cord

The distribution of mu opioid receptors was studied in human fetal spinal cords between 12–13 and 24–25 wk gestational ages. Autoradiographic localisation using [³H] DAMGO revealed the presence of mu receptors in the dorsal horn at all age groups with a higher density in the superficial laminae (I–II). A biphasic expression was noted. Receptor density increased in the dorsal horn, including the superficial laminae, between 12–13 and 16–17 wk. This could be associated with a spurt in neurogenesis. The density increased again at 24–25 wk in laminae I–II which resembled the adult pattern of distribution. A dramatic proliferation of cells was noted from the region of the ventricular zone between 16–17 and 24–25 wk. These were considered to be glial cells from their histological features. Mu receptor expression was noted over a large area of the spinal cord including the lateral funiculus at 24–25 wk. This may be due to receptor expression by glial cells. The study presents evidence of mu receptor expression by both neurons and glia during early development of human spinal cord.     

A study of motoneuron groups and motor columns of the human spinal cord

Eight normal human spinal cords were studied for motoneuron (Mn) groups and columns. Spinal segments (C1 to Coc.) were identified and embedded in paraffin wax. Serial cross sections were cut at 25 μm and stained by cresyl violet. Cross-sectional profiles of the spinal cord were traced for each segmental level and the outlines of the various Mn groups superimposed. These charts (maps) were used to examine intra and intersegmental changes in the relative positions of the columns. An attempt was made to provide topographical picture of Mn groups of individual segments. In the cervical region neuronal groups were more numerous but smaller and less distinct, while in the lumbosacral region they were fewer, larger and at many levels better circumscribed. The average number of Mn groups at any segmental level was 3–4 and never exceeded 5. C4, C5, C6, C7, L4, L5 and S1 contained numerous Mn groups. Maximum intrasegmental changes were noted at C3, C4, C7, T1, and S2, while at C5, C6, all thoracic, L1 L2 and L3, the pattern was constant throughout the segment. Eleven motor columns were traced in the human spinal cord. Column 1 belonged to the medial division and columns 2–11 to the lateral division of the ventral grey horn. Columns 1 and 2 were the most extensive as they were traceable from the lower medulla to S3 segment. Columns 3–8 were confined to cervical segments (including T1), while columns 9–11 were traced in lumbosacral segments. In general, motor columns followed a definite mode for their appearance and disappearance. Many of them showed rotation from a dorsal to a ventromedial direction.     

Cell death in developing human spinal cord

Cell death in the developing human spinal cord was investigated in 5–12 week human conceptuses using immunohistochemical and TUNEL methods. Expression of pro-apoptotic (Fas-receptor, caspase-3) and anti-apoptotic (bcl-2) markers and marker for internucleosomal fragmentation (TUNEL) were analysed in the cranial and caudal parts of the human spinal cord. In early developmental stages (5–6 weeks) of the cranial spinal cord, bcl-2 positive cells were seen in the ventricular zone and in the roof plate, while in the caudal part they were seen surrounding the central lumen. Subsequently, bcl-2 expression appeared in the basal plates of the grey matter and in the spinal ganglia, and from the seventh week on they also appeared in the intermediate horn of the grey matter. In the fetal period, bcl-2 expression appeared in the dorsal horns of the grey matter (9 weeks) but ceased in the ventricular zone (12 weeks) . In the trunk region, TUNEL-positive cells were found in ventricular and mantle zones along the whole length of the spinal cord. Caspase-3 positive cells and Fas-receptor positive cells appeared only in the grey matter of the cranial segments (head and trunk) of the spinal cord, but they were missing in the caudal parts. Caspase-3 dependant pathway, probably activated by Fas-receptor, seems to operate only in the cranial part of the human spinal cord. In the caudal (sacrococcygeal and tail) parts, cells seem to die by caspase-3 independent pathway. The interplay of pro-apoptotic and anti-apoptotic factors may be associated with cranial spinal cord morphogenesis, adjustment of cells number and selective survival of neurons, while in the caudal regions these factors cause massive cell death associated with regression of the caudal spinal cord.     

Effect of developing insulin hypoglycemia on monosynaptic spinal reflexes in cats

Acute experiments on anesthetized and spinal cats showed that deepening insulin hypoglycemia causes inhibition of rhythmic monosynaptic EPSPs of motoneurons in the lumbar region of the spinal cord. In the initial period of hypoglycemia (a fall of the blood sugar to 50–60 mg%) the progressive decrease in the efficiency of trans-synaptic processes was not caused by pre-or postsynaptic inhibition or by depression and was due to exhaustion of the operative fraction of mediator. In deeper hypoglycemia the functions of the postsynaptic formation of the monosynaptic spinal reflex arc are disturbed.Laboratory of Physiology of the Autonomic Nervous System, I. P. Pavlov Institute of Physiology, Academy of Sciences of the USSR, Leningrad. (Presented by Academician V. N. Chernigovskii.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 87, No. 4, pp. 305–308, April, 1979.