人周围神经内乙酰胆碱酯酶活性与神经束性质的鉴别

本文用Karnovsky乙酰胆碱酯酶组织化学方法,系统地观察了成人周围神经中乙酰胆碱酯酶的分布。材料包括20侧上肢主要神经干及其分支、部分下肢神经的肌支和皮支、6侧C_7脊神经前后根。皮神经内,有髓纤维酶反应阴性;大量无髓纤维显示强阳性酶反应,呈群块状分布。肌支神经内58%的有髓纤维酶反应阳性,酶活性局限于轴索内,髓鞘不显酶活性;示强阳性酶反应的无髓纤维远较皮神经少。C_7脊神经前根87%有髓纤维酶反应阳性,与肌支内酶反应阳性有髓纤维相似;后根纤维酶反应阴性;灰交通支内酶反应强阳性,与皮支内阳性无髓纤维酶染色强度一致。本文结果表明,周围神经运动束和感觉束内,有髓及无髓纤维酶活性都有明显不同;明确提出,酶染色有髓纤维来源脊神经前根运动纤维,具有强酶活性的无髓纤维是交感神经节后纤维。     

Microanatomy and number of nerve fibres of the lower intercostal nerves with respect to a nerve anastomosis. Donor nerve analysis. I. (IV).

A human intercostal nerve has about 10,000 myelinated nerve fibres, of which about 1000 to 2000 are motor. At about the axillary line the nervus intercostalis splits into the ramus cutaneous lateralis and a deep branch to the musculus rectus abdominis and other muscles. The ramus cutaneous lateralis consists of 2 skin branches of about 3000 nerve fibres and a muscle branch to the musculus obliquus externus of about 400 to 1100 nerve fibres. The deep branch to the musculus obliquus internus, the musculus transversus and the musculus rectus abdominis and the anterior skin consists of about 2500 to 7000 fibres of which 400 to 1700 are skin fibres. There is indication that the muscle branch to the musculus obliquus externus has about 50% motor fibres. The intercostal nerve is, as it splits after about 20 cm into 4 branches, a suitable donor of at least 2 different muscle functions and a skin sensible function for a direct nerve anastomosis. A crude model for calculating matching probabilities of motor and sensory fibres between donor and acceptor nerves is introduced. Besides the importance of having enough donor nerve fibres, it is calculated that the small amount of motor nerve fibres can be best used if muscle branches of the donor nerves are connected to muscle branches of the acceptor nerves. Because of the separation between normal laboratory animals and humans on the phylogenetic scale, differences in regeneration and plasticity are discussed.     

Human phrenic nerve: analysis of nerve fibre types on the base of their acetylcholinesterase activity (author's transl)

As marked differences in the Acetylcholinesterase (ACHE)-activity of myelinated nerve fibres of ventral and dorsal spinal roots can be found also in human post mortem material (ZENKER et al. 1978), the Karnovsky-method for histochemical demonstration of ACHE-activity has been used for differentiation of motor and sensory fibres in the human phrenic nerve. In cross sections of the phrenic nerve 1--2 cm above its entrance into the diaphragm, after an incubation period of 24 hours, 86% of the medullated nerve fibres displayed a high enzyme activity and therefore were classified as motoric. The histogram of these stained fibres revealed a large group of fibres with a peak at 9--10 micron in diameter which were interpreted as A-alpha fibres and a small group of fibres with a peak at 2--3 micron which were classified as A-gamma fibres. The mean diameter of the A-alpha group fibres is smaller than the mean diameter in a "typical" muscle nerve. Furthermore, the number of A-gamma fibres in the phrenic nerve, as compared with a "typical" muscle nerve is strikingly small. This seems to be in accordance with the small number of unstained fibres (14% only) which were interpreted as sensoric. In this group no fibre was found larger than 9 micrometers in diameter. This could mean a complete lack of primary afferents within the human phrenic nerve.     

Morphology of the long and short uveal nerves in the human eye

The aim of this study was to examine the architecture of the uveal nerves in the sclera and suprachoroid of human eyes. Eyes from 17 adult human donors were investigated. The uveal nerves in different regions (retrobulbar, intrascleral, suprachoroidal, pars plana) were prepared and studied by light and electron microscopy. In addition, immunohistochemistry was performed for various neuronal markers. The long uveal nerves showed a characteristic suprachoroidal location with no branches supplying the choroid. It was found that typically they are composed of myelinated (75%) and non-myelinated (25%) nerve fibres. They mainly contain aminergic and sensory nerve fibres. A separate set of cholinergic non-myelinated nerve fibre bundles runs parallel with these long uveal nerves. The short uveal nerves supply the suprachoroidal nerve plexus with approximately 13% of their nerve fibres. The nerves and the branches supplying the choroid appear as mixed nerves containing sympathetic, parasympathetic and sensory axons. This study therefore provides new information about the quantity, type and distribution of myelinated and non-myelinated nerve fibres in the posterior uvea of the human eye.     

Fiber composition of the rat sciatic nerve

The rat sciatic nerve originates from the spinal segments L4-L6. It is unifascicular at the trochanter; 5-7 mm distally, the nerve splits into two and then into four fascicles. The tibial portion gives rise to the tibial and the sural nerves, and the peroneal portion gives rise to the peroneal nerve and a cutaneous branch that perforates the lateral hamstring muscles to innervate the proximolateral face of the calf. The number and type of the axons in these branches were determined in light and electron micrographs of normal nerves, and after de-efferentation or sympathectomy. Deafferentation was technically not feasible because spinal ganglia and ventral roots were supplied by the same vascular plexus. The tibial nerve contained 1,000 motor and 3,500 myelinated afferent axons, 3,700 sympathetic axons, and 5,400 unmyelinated afferent axons. The peroneal nerve contained 600 motor and 1,300 myelinated afferent axons, 1,100 sympathetic axons and 3,000 unmyelinated afferent axons. The sural nerve contained 1,100 myelinated and 2,800 unmyelinated afferent axons; in addition, there were 1,500 unmyelinated sympathetic axons. The cutaneous branch consisted of 400 myelinated and 1,800 unmyelinated afferent axons. Thus, the entire sciatic nerve at midthigh is composed of about 27,000 axons; 6% are myelinated motor axons, 23% and 48% are myelinated and unmyelinated sensory axons, respectively, and 23% are unmyelinated sympathetic axons. The techniques used did not demonstrate sympathetic axons in the cutaneous branch and did not reveal the few motor axons contained in the sural nerve.     

Different multiple regeneration capacities of motor and sensory axons in peripheral nerve

Abstract After peripheral nerve injury, axons often project sprouts from the node of Ranvier proximal to the damage site. It is well known that one parent axon can sprout and maintain several regenerating axons. If enough endoneurial tubes in the distal stump are present for the regenerating axons to grow along, then the number of mature myelinated nerve fibers in the distal stump will be greater than the number in the proximal stump. "Multiple regeneration" is used to describe this phenomenon in the peripheral nerve. According to previous studies, a prominent nerve containing many axons can be repaired by the multiple regenerating axons sprouting from another nerve that contains fewer axons. Most peripheral nerves contain a mixture of myelinated motor and sensory axons as well as unmyelinated sensory and autonomic axons. In this study, a multiple regeneration animal model was developed by bridging the proximal common peroneal nerve with the distal common peroneal nerve and the tibial nerve. Differences in the multiple regeneration ratio of motor and sensory nerves were evaluated using histomorphometry one month after ablating the dorsal root ganglion (DRGs) and ventral roots, respectively. The results suggest that the motor nerves have a significantly larger multiple regeneration ratio than the sensory nerves at two different time points.     

Motor unit numbers,motor unit sizes and innervation of single muscle fibres in hyperinnervated adult mouse soleus muscle

The sural and the lateral plantar nerves were implanted simultaneously into the denervated soleus muscle of adult mice. Each of these nerves contained approximately the normal number of soleus motor axons. This procedure therefore allowed a study of how an initial excessive number of motor axons provided by two different, foreign nerves and terminating into the soleus muscle affected the final pattern of muscle innervation. In muscles examined two months or more after the implantation of the foreign nerves all muscle fibres were innervated. The fraction of the muscle innervated by either nerve varied widely from one preparation to another. However, all the motor axons which were implanted into the muscle appeared to make permanent synapses. Moreover, the distribution of motor unit sizes of each foreign nerve relative to the total number of muscle fibres innervated by that nerve was similar to the distribution of motor unit sizes in muscles cross-innervated by that nerve alone, although the absolute motor unit sizes were reduced. Estimated by intracellular recording, 20–30% of the muscle fibres were polyneuronally innervated. A similar fraction of teased muscle fibres stained for acetylcholinesterase had more than one endplate.     

肋间臂神经的解剖及其临床意义

目的：为乳癌腋清扫术中保留肋间臂神经(ICBN)提供解剖学基础。方法：对25具成人尸体的50侧腋区进行了解剖，对肋间臂神经及上下相邻皮神经的走行、分支、支配、粗细等情况进行解剖观察。结果：ICBN可分为缺如型、单干型、单干分支型、双干型及3干型；84％的臂内侧皮神经与ICBN上支、上干相交通；34％的第3肋间神经外侧皮支可发支支配腋窝底；3侧第1肋间神经外侧皮支主干进入上臂内侧。结论：肋间臂神经为第2肋间神经外侧皮支的分支，通常为上支或上干，与臂内侧皮神经联合构成，可有第3或第1肋间神经的外侧皮支参与。其损伤可造成乳房切除术后疼痛综合征，乳癌腋清扫术中经胸小肌后方或经腋静脉下方能顺利找到该神经并加以保护。     

Regeneration and retrograde degeneration of axons in the rat optic nerve

Summary The retinal stump of the rat optic nerve was examined histologically 1–64 weeks after intracranial section of the nerve with or without grafting of autologous peripheral nerve segments. Single unmyelinated axons and bundles of unmyelinated axons appeared in cut optic nerves and were most abundant 2–4 weeks after section. With light and electron microscope radioautography after injection of tritiated amino acids into the globe, it was confirmed that many unmyelinated fibres arose from the optic nerve rather than from nearby peripheral nerves and it was estimated that some axons regenerated as far as 0.5 mm. At or near the end of retinofugal axons, structures resembling growth cones were seen at 2 weeks and vesicle-containing swellings similar to synapses were found at 1–2 months. Outgrowth from optic nerve axons was not obviously enhanced by peripheral nerve grafts although a few retinofugal axons became ensheathed by Schwann cells. Retrograde axonal degeneration was rapid in both cut and grafted optic nerves, the number of nerve fibres near the globe falling to less than 10% of normal after 4 weeks. A few myelinated and unmyelinated fibres were still present 64 weeks after nerve transection. In conclusion, some cut axons in the rat optic nerve display a transient regenerative response before undergoing retrograde degeneration.     

Fiber arrangements of nerves belonging to ventral and dorsal divisions in the proximal region of the brachial plexus: a study using fluorescence of DiI and DiO in adult rats

The motor and sensory fiber arrangements in the proximal region of the spinal nerves are important for understanding the relationship of the peripheral nerves to neuron distribution. On the other hand, the fiber arrangements are also important for the treatment of peripheral nerve grafting. We studied the fiber arrangements of two divisions (ventral and dorsal) in the proximal region of the brachial plexus and the fiber arrangements of the lateral cutaneous rami in Th7 and Th8 intercostal nerves in adult rats with a method using the fluorescent pigments DiI and DiO. Results showed that fiber arrangements belonging to the two divisions have a specific separate distribution in the distal region. However, this specific separate distribution form was absent in the proximal region of the spinal nerves in the plexus. Fiber arrangements of the lateral cutaneous ramus in the anterior branches of the thoracic nerves (intercostal nerves) were also observed in comparison with those in the brachial plexus by the same method. In the intercostal nerves, fibers of the lateral cutaneous ramus were distributed in the dorsal portion from distal to proximal. These results suggest that there are two types of fiber arrangement in the proximal regions of the spinal nerves: a ventrodorsal distributional type, comprising intercostal nerves and the dorsal branches of the spinal nerves; and a mixed type, comprising the anterior branches of the cervical and brachial (and perhaps lumbar) plexuses. On the other hand, fibers of the lateral cutaneous rami in the intercostal nerves were distributed on the dorsal part of the nerves. These results of fiber arrangement analysis for the intercostal nerves may offer an opportunity to improve the effect of treatments using peripheral nerve grafting and suturing in the brachial and lumbar plexus with intercostal nerves.     

A note on the limb nerves of the frog (Rana tigrina)

In the frog (Rana tigrina) the mean length of the brain was 17.5 mm and that of the spinal cord 61 mm. The weight of the brain and spinal cord (together) was 389 mg. The fascicular number, fascicular area, total number of fibres and their density were studied in the left and right brachial nerves, left and right sciatic nerves and the sympathetic trunk (nerve). The largest number of nerve fascicles (12) was noticed in the sympathetic trunk while the right brachial nerve comprised of only one nerve fascicle. As for the mean fascicular area, the left brachial nerve had the greatest area (0.7963 mm2) while the least (0.1312 mm2) was noticed in the sympathetic trunk. The sympathetic trunk revealed the highest number (mean value 2176) of myelinated fibres. The least value in this regard (598) was noticed in the left sciatic nerve. As for the external diameter of the nerve fibres, more than 50% of the fibres in all the nerves were of the order 6--8 micrometer. The histograms confirmed this trend. The greatest density of myelinated nerve fibres was noted in the left brachial nerve (288/mm2). Based on the retrograde degeneration, the ventral horn neurons giving origin to the motor fibres in the brachial nerves were traced to spinal cord segments 2 (Preponderantly) and 3. The ventral horn neurons of spinal cord segments 7 and 8 appear to contribute motor fibres to the sciatic nerves.     

Light and electron microscopic distribution of nerve growth factor receptor-like immunoreactivity in the skin of the rat lower lip.

Nerve growth factor receptor distribution in the skin of the adult rat was studied by immunocytochemistry with the use of the monoclonal antibody 192-IgG. Immunoreaction occurred in a patchy pattern in the epidermis and outer root sheaths of hair follicles, as well as in nerves and in capsulated and non-capsulated sensory receptors. Electron microscopic analysis revealed that the areas of patchy epithelial immunostaining corresponded to the plasma membrane of groups of keratinocytes, which were always associated with intra-epithelial nerve fibres. Immunostaining was also associated with Merkel cells, hair follicle receptors, and the capsular cells of capsulated receptors. In the nerves, immunostaining was detected in perineurial cells and axons. After sensory denervation of the skin, immunostaining decreased considerably in the epithelia, as well as in the small nerves, although short segments of increased staining were observed in the latter. In larger nerves, immunostaining was markedly increased and mainly associated with newly formed Schwann cell processes. After sympathetic denervation, the pattern of immunostaining was identical to controls, except for augmented immunoreactivity in short segments of degenerating nerves around blood vessels and smooth muscle fibres. From these observations, it is suggested that the epithelial and perineurial cells synthesize and express nerve growth factor receptors, while receptors present in nerve fibres originate from the nerve cell bodies in the gasserian ganglion.     

成年女性乳头乳晕神经复合体解剖学特点及临床意义

目的　研究成年女性乳头乳晕区神经来源及其分布情况,指导临床实践,尽可能保留乳头乳晕感觉功能。 方法　对8具成年女性尸体的15侧乳房标本进行大体解剖学研究,应用显微手术器械对乳头乳晕区的神经来源、分布进行追踪探查。 结果　肋间神经前皮支和外侧皮支共同构筑了乳头乳晕区神经网。15侧标本乳头乳晕区神经支配均由第3及第4肋间神经前皮支及第4和第5肋间神经的外侧皮支共同支配,其中第4肋间神经外侧皮支分布占据整个乳晕区神经分布约75%。 结论　乳头乳晕区神经分布广泛,呈现互补性,当第3或第5肋间神经受损时,乳头乳晕仍保留有大部分感觉功能。     

腹外斜肌的神经入肌点定位与肌内神经分布研究

目的　对人腹外斜肌的神经入肌点定位和肌内神经染色观察，为其临床应用提供形态学资料。 方法　成尸11具定位神经入肌点和5具行Sihler’s 肌内神经染色。 结果　腹外斜肌受下8对肋间神经外侧肌支支配，各个肌齿的神经入肌点距离相应肌齿起端中点(1.54±0.33)cm，位于锁骨中线与第5肋下缘的交界处至腋后线与第11肋下缘交界处的连线上。Sihler’s染色显示支配腹外斜肌的肋间神经外侧肌支入肌后分出小分支分布到各肌齿的起端1/3，然后约在各肌齿的近、中1/3交界处分出2支二级神经分支，即上支与下支，它们分出小分支分布到各肌齿的中间1/3，相邻两个肌齿的上支与下支在各肌齿中远部形成“U”形吻合，从“U”形吻合弓上分出小分支分布到各肌齿的止端1/3。在腹外斜肌上半部，各肌齿的神经分支分布到相应的肌齿，但在腹外斜肌下半部，上一肌齿的远侧下份是由下一肌齿的神经分支(上支)分布。 结论　①为临床上腹壁局部麻醉和术后切口疼痛的神经阻滞提供指导意义；②腹外斜肌中远部从上至下形成“波浪形”的神经分支密集区；③腹部手术切口建议不要超过四个肌齿。     

Anatomical study of innervated transverse rectus abdominis musculocutaneous and deep inferior epigastric perforator flaps

The present study investigated anterior cutaneous branches of the 10th, 11th and 12th intercostal nerves. Innervated transverse rectus abdominis musculocutaneous (TRAM) flap and deep inferior epigastric perforator (DIEP) flap are often used in breast reconstruction. To innervate these flaps effectively, the appropriate anterior cutaneous branches of intercostal nerves must be selected. Dissection of 40 sides of 20 cadavers (5 male, 15 female) was performed. Nerves were classified into four groups according to vertical location from rectus abdominis (RA) entry points. Group 1 was situated from 0-19% of the umbilicus-to-pubic tubercle distance; Group 2, 20-39%; Group 3, 40-59%; and Group 4, 60-79%. Mean number of nerves per side was 1.4 in Group 1, 1.2 in Group 2, 1.1 in Group 3 and 0.2 in Group 4. The arcuate line was situated 32 +/- 9% below the umbilicus. Group 3 and 4 nerves tended to enter the RA more laterally than Group 1 nerves. Most nerves separated into 1-2 cutaneous branches while branching off several muscular branches. Several nerves in Groups 1 and 2 displayed no cutaneous branches. More muscular branches were present in Groups 1 and 2 than in Groups 3 and 4. Distance from lateral edge of the RA sheath to RA entry point was longer in Groups 1 and 2 than in Group 4. Cutaneous points, indicating entry points of a nerve into the dermis, were situated slightly more inferior than RA entry points. To innervate flaps effectively, a nerve entering the RA slightly superior to the expected sensory recovery area should be chosen. Clinically, Group 1 or 2 nerves seem to be selected in many TRAM or DIEP flap cases. If the cutaneous branch in Group 3 or 4 is easy to separate from RA, this can be included in the flap along with a main nerve, and might enable the flap to recover sensation in a wider area or reinforce the occasional lack of a sensory branch from Group 1 or 2. The present findings provide the basis for more precise dissection of TRAM and DIEP flaps, and should facilitate reliable preservation of sensation in flaps.     

Re-innervation of twitch and slow muscle fibres of the frog after crushing the motor nerves.

1. The conduction velocities of individual motor axons innervating twitch and slow muscle fibres of the frog were determined by intracellular recording of junctional potentials elicited by stimulating the motor nerves at two different points. 2. In normal pyriformis muscles twitch and slow fibres were found to be innervated by two distinct populations of motor axons. Twitch fibre axons conducted at 10-18-7 m/sec, while the conduction velocities of slow fibre axons ranged from 0-5 to 5 m/sec (at 7-9 degrees C). The thresholds for electrical stimulation were significantly lower in the fast than in the slow axons population. 3. Following denervation by crushing the sciatic nerve fast axons which re-innervated the muscle had lower conduction velocities than normal but could still be identified. These lower conduction velocities were measured proximal to the site of the crush and did not recover over a period of 446 days. 4. Fast motor axons regenerated more quickly than slow axons and re-innervated twitch as well as slow muscle fibres non-selectively. About 1 month later slow axons re-established synaptic contacts with slow (and some twitch) muscle fibres. Simultaneous re-innervation by fast and slow motor axons was occasionally observed in slow muscle fibres. Finally, the slow muscle fibres were innervated by slow axons only, while synapses of fast axons could no longer be found in this type of muscle fibre. 5. Action potentials were observed in denervated as well as in re-innervated slow muscle fibres; they disappeared as re-innervation progressed. 6. It is concluded that non-selective re-innervation of slow muscle fibres is present in the frog; it is, however, a transient phenomenon followed by restoration of the original innervation pattern.     

Sodium channel inactivation kinetics of rat sensory and motor nerve fibres and their modulation by glutathione

Na⁺ channel currents of rat motor and sensory nerve fibres were studied with the patch-clamp technique on enzymatically demyelinated axons. Differences between motor and sensory fibres in multi-channel inactivation kinetics and the gating of late single-channel currents were investigated. In the axon-attached mode, inactivation of multi-channel Na⁺ currents in sensory axons was best fitted with a single time constant while for motor axons two time constants were needed. Late single-channel currents in sensory axons were characterized by short openings whereas motor axons exhibited additional long single-channel openings. In contrast, in excised, inside-out membrane patches, no differences between motor and sensory fibres were found: in both types of fibre inactivation of multi-channel Na⁺ currents proceeded with two time constants and late single-channel currents showed short and long openings. After application of the reducing agent glutathione to the cytoplasmic side of excised inside-out patches, inactivation of Na⁺ currents in both motor and sensory fibres proceeded with a single, fast exponential time constant and late currents appeared with short openings only. These data indicate that the axonal metabolism may contribute to the different inactivation kinetics of Na⁺ currents in motor and sensory nerve fibres.     

Morphometric analysis of the human trigeminal nerve.

We evaluated the components of nerve fibers of the motor and sensory roots of the trigeminal nerve by morphometric analysis. Trigeminal nerves were obtained from 5 cadavers (males, aged 67-95) were stained by Masson-Goldner-Goto method and examined under the microscope using a morphometric image-analyzer. The area and perimeter of axons were larger in the motor root than in the sensory root. The size distribution of axons was wider in the motor root than in the sensory root and the distribution pattern was unimodal type. These findings suggested that nerve fibers of the human trigeminal nerve gave similar findings to those of other peripheral nerves, regarding axonal size distribution and relative size of motor and sensory nerve axons.