人胎大肠氮能神经元发育的研究

用NADPH-d组织化学法对人胎大肠氮能神经元的发育进行了观察.结果表明第5个月胎龄时,肌间神经节处圆形细胞中部分细胞出现一氧化氮合酶(NOS)阳性反应,并分化成氮能神经细胞.第6个月胎龄时,氮能神经元胞体增大,突起伸长,在肌层、粘膜下层和肠腺基部出现氮能神经纤维分布.第7个月胎龄时,氮能神经元生长发育达到高峰,肌间神经节细胞数目增多,环肌层神经纤维分布密度增加,膨体结构明显.第8-10个月胎龄时,氮能神经元染色强度加深,其胞体分布以肌间神经节最多,粘膜下层和内环肌层较少.氮能神经纤维的分布密度以内环肌层最高,粘膜下层和外纵肌层次之,粘膜层较低.本研究揭示了大肠氮能神经元发育的变化规律.     

A histological study on the coronary artery of the indigenous black Bengal goat in Bangladesh.

The coronary artery of the black Bengal goat was studied by light microscopy. The wall of the coronary artery consisted of the tunica intima, tunica media and tunica externa. The tunica intima consisted of a single layer of flattened endothelium. The tunica media was well-developed and composed of mainly of smooth muscle cells together with some fine elastic fibers. The tunica externa consisted of predominant collagen fibers, and some elastic fibers and smooth muscle cells. Elastic fibers in the tunica externa formed a circular arrangement around the tunica media. Sex differences were not observed. The media with well-developed smooth muscle cells may be responsible for changes in functional physiological conditions of the heart.     

Distribution and the fine structure of serotonin-containing fibers in the rat small intestine

Serotonin immunoreactive fibers were observed under the electron microscopy in all layers of the small intestine, with greatest abundance in the mucosa. Submucosal blood vessels were often surrounded by immuno positive nerves. In the inner circular muscle layer the immunoreactive serotonin positive fibers were closely associated with the smooth muscle cells. In the ganglia of the myenteric and submucous plexuses, labelled fibers surrounded the immunonegative neural cell bodies, but rarely formed conventional synaptic junctions. It is concluded that the serotoninergic system of the small intestine may influence the activity of associated structures in a diffuse non-synaptic manner.     

Study of neuropeptide Y-containing nerve fibers in the human penis

Summary Neuropeptide Y 1–36 (IR-NPY) immunoreactive nerve-fiber processes have been observed in tunicae of veins and arteries and in smooth muscles of the human penis taken at autopsy or during surgery by use of light-and electron-microscopic immunohistochemical techniques. Numerous IR-NPY nerve fibers were mostly concentrated in the inner part of the adventitia close to the media of the arterial and venous vessels and among the intracavernous smooth muscle cells. IR-NPY nerve fibers were less abundant in veins than in arteries. Positive somata were not observed in the penises. At the ultrastructural level, IR-NPY were localized exclusively in large, dense granules of nerve terminals by means of the postembedding immunogold technique. In the deep dorsal vein, IR-NPY nerve fibers were also located in the media formed by an outer circular and an inner longitudinal layer. In the intracavernous and dorsal arteries, they showed the highest density in the inner part of the adventitia. In the corpora cavernosa and in the corpus spongiosum, IR-NPY nerve processes were intermingled between the smooth-muscle fibers around the sinusoid spaces. IR-NPY nerve fibers were present in the cavernous nerves close to the central arteries. The urethra did not show any IR-NPY-positive nerve fibers. This peculiar distribution of IR-NPY nerve fibers suggested that they could participate in regulating arterial and venous blood flow and intracavernous smooth-muscle tone. NPY may therefore be of importance in some of the mechanisms of penile erection especially during detumescence.     

人胎大肠氮能神经元发育的研究

By using histochemical methed of NADPH-diaphorse, the development of the nitrergic neurons in the large intestine of human fetus were studied. The results showed: At the fifth month of gestation, weak positive reaction of nitric oxide synthase (NOS) appeared in part of the round cells of intermuscular ganglia. The round cells differentiated into the nitrergic nerve cells. At the sixth month, the bodies of nitrergic neurons were obviously enlarged, the processes of which were lengthened. The nitrergic nerve fibers were seen in the muscle layer, the submucosa and the base of the intestinal gland. The growth and development of nitrergic neurons reached its peak at the seventh month. The number of intermuscular ganglionic cells was increased. The density of nitrergic nerve fibers was increased in the inner circular muscle layer, and have bead-like structures. At the eighth to tenth month, the staining intensity of nitrergic neurons was increased. The myenteric plexus was densely distributed with nitrergic nerve cell bodies, whereas the submucosa and the inner circular muscle layers contained only a few neurons. The nitrergic nerve fibers were observed in all layer of large intestine, the density of the distribution of nitrergic nerve fibers was by far the highest in the inner circular muscle layer, less in the submucosa and outer longitudinal muscle layer, and only a few were found in the mucous layer. To our knowledge, it is the first time that the development of nitrergic neurons in the large intestine of human fetus was demonstrated.     

Light,electron microscopical,and immunocytochemical investigation of the stomach wall of the tigerfish Hydrocynus forskahlii

The wall of the stomach of the tigerfish is described and compared with that of other vertebrates. Light microscopic and ultrastructural characteristics of the stomach wall correspond to a large extent to those of other vertebrates, although some differences are found. The mucosa contains (1) surface epithelium characterized by narrow columnar cells with abundant mucous granules; (2) gastric glands consisting of pepsinogenic cells of variable height, containing tubulovesicles and bearing microvilli; (3) five granulated cell types located basally in the epithelium (types 1–5); and (4) lamina propria and muscularis mucosae. Connective tissue separating smooth muscle fibers of the muscularis mucosae constitutes a stratum compactum. The submucosa contains a loose connective tissue, a tunica muscularis of inner circular and outer longitudinal layers, and a serosa of mesothelium and subjacent connective tissue. Immunocytochemical tests with antisera to five polypeptides show gastrin/cholecystokinin (CCK), vasoactive intestinal polypeptide (VIP) immunoreactivities in some cells of the gastric glands, and somatostatin in cells lying among epithelial cells lining the gastric luminal surface or gastric pits.     

Ultrastructural analysis of spinal primary afferent fibers within the circular muscle of the cat lower esophageal sphincter

We have analyzed the ultrastructural characteristics and environment of spinal primary afferent fibers that run within the circular muscle of the cat lower esophageal sphincter. These were selectively labeled by anterogradely transported cholera toxin B subunit conjugated with horseradish peroxidase. Most of the labeled fibers were perpendicular to the muscle cells but some ran sinuously or parallel to the muscle cells. All the labeled fibers were unmyelinated and exhibited relatively rare varicosities. Most of the fibers were in large nerve fiber bundles surrounded by perineurium and probably project to the mucosa. Only some fibers that were in small nerve fiber bundles with no perineurium ran parallel to the musculature and established close relationships with smooth muscle cells. They might be a small subpopulation of the spinal tension receptors, most of the other spinal tension receptors being located in the myenteric plexus area, between the circular and longitudinal muscle. Accepted: 2 December 1999     

A comparative anatomical study of the mammalian uterotubal junction

Among eight species of mammals in this study (cattle, sheep, pig-tail and rhesus monkeys, rabbit, pig, rat, and dog) four basic patterns of anatomical structure at the uterotubal junction are described. The classification of types is based upon the presence or absence of an intramural portion of the oviduct and of isthmal folds or plicae projecting into the lumen of the uterine cornu. Histological variations are reported for three tissues: epithelial and connective of the mucosa and smooth muscle of the tunica muscularis. In the epithelium during the estrous cycle the differences recorded include: (a) absence of ciliated cells in the distal end of the oviduct in rat and dog; (b) variations in ciliated and nonciliated cells in (1) cell height, (2) location, shape and stainability of the nucleus, and (3) in amount and stainability of apical cytoplasm; (c) presence of lymphoblast-like cells which appear to migrate through the epithelium from the lamina propria. The connective tissue of the mucosa, as a circular layer and as cores for the mucosal folds, shows variations in thickness and in relative density of cells and fibers of the matrix. Emphasis is given to the presence of an inner longitudinal layer of smooth muscle in the tunica muscularis of the distal oviduct in six of the eight species.     

The ultrastructure and distribution of 5-HT-containing neurons in the intestine of a teleost fish,Aldrichetta forsteri

Summary The intestine of Aldrichetta forsteri was examined ultrastructurally for evidence of 5-HT-containing intrinsic neurons. A population of nerve cell bodies and processes characterized by the presence of amine-containing vesicles was found after the destruction of adrenergic processes with 6-hydroxydopamine. The distribution of the neurons matched that of the 5-HT-containing neurons previously seen with formaldehyde-induced fluorescence and 5-HT immunohistochemistry in A. forsteri and other teleosts. The axons made close contacts with the circular smooth muscle layer and the muscularis mucosae. The axons also lay exposed to the epithelial cells of the mucosa but did not make contact with neurons or with the longitudinal smooth muscle layer.     

Nitric oxide synthase immunoreactivity in the enteric nervous system of the developing human digestive tract

We have investigated indirectly the presence of nitric oxide in the enteric nervous system of the digestive tract of human fetuses and newborns by nitric oxide synthase (NOS) immunocytochemistry and nicotinamide adenine dinucleotide phosphate diaphorase (NADPHd) histochemistry. In the stomach, NOS immunoactivity was confined to the myenteric plexus and nerve fibres in the outer smooth musculature; few immunoreactive nerve cell bodies were found in ganglia of the outer submucous plexus. In the pyloric region, a few nitrergic perikarya were seen in the inner submucous plexus and some immunoreactive fibres were found in the muscularis mucosae. In the small intestine, nitrergic neurons clustered just underneath or above the topographical plane formed by the primary nerve strands of the myenteric plexus up to the 26th week of gestation, after which stage, they occurred throughout the ganglia. Many of their processes contributed to the dense fine-meshed tertiary nerve network of the myenteric plexus and the circular smooth muscle layer. NOS-immunoreactive fibres directed to the circular smooth muscle layer originated from a few NOS-containing perikarya located in the outer submucous plexus. In the colon, caecum and rectum, labelled nerve cells and fibres were numerous in the myenteric plexus; they were also found in the outer submucous plexus. The circular muscle layer had a much denser NOS-immunoreactive innervation than the longitudinally oriented taenia. The marked morphological differences observed between nitrergic neurons within the developing human gastrointestinal tract, together with the typical innervation pattern in the ganglionic and aganglionic nerve networks, support the existenc of distinct subpopulations of NOS-containing enterice neurons acting as interneurons or (inhibitory) motor neurons.     

Projections of neurochemically specified neurons in the porcine colon

The intramural projections of nerve cells containing serotonin (5-HT), calcitonin gene-related peptide (CGRP), vasoactive intestinal peptide (VIP) and nitric oxide synthase or reduced nicotinamide adenine dinucleotide phosphate diaphorase (NOS/NADPHd) were studied in the ascending colon of 5- to 6-week-old pigs by means of immunocytochemistry and histochemistry in combination with myectomy experiments. In control tissue of untreated animals, positive nerve cells and fibres were common in the myenteric and outer submucous plexus and, except for 5-HT-positive perikarya, immunoreactive cell bodies and fibres were also observed in the inner submucous plexus. VIP- and NOS/NADPHd-positive nerve fibres occurred in the ciruclar muscle layer while VIP was also abundant in nerve fibres of the mucosal layer. 5-HT- and CGRP-positive nerve fibres were virtually absent from the aganglionic nerve networks. In the submucosal layer, numerous paravascular CGRP-immunoreactive (IR) nerve fibres were encountered. Myectomy studies revealed that 5-HT-, CGRP-, VIP- and NOS/NADPHd-positive myenteric neurons all displayed anal projections within the myenteric plexus. In addition, some of the serotonergic myenteric neurons projected anally to the outer submucous plexus, whereas a great number of the VIP-ergic and nitrergic myenteric neurons send their axons towards the circular muscle layer. The possible function of these nerve cells in descending nerve pathways in the porcine colon is discussed in relation to the distribution pattern of their perikarya and processes and some of their morphological characteristics.     

Intrinsic innervation in the tracheal smooth muscle of the large flying fox (Pteropus vampyrus): an immunohistochemical study

Structure and innervation of the trachea of the large flying fox (Pteropus vampyrus) were examined by mean hematoxylin-eosin staining and immunohistochemical methods. The tracheal rings were predominantly comprised of bone with a small amount of hyaline cartilage. Bone contained bone marrow and hyaline cartilage attached at the ends of the tracheal rings. The tracheal rings in the anterior third of the trachea were connected at each end with connective tissue to almost form a ring. A narrow membranous wall comprising a single layer of smooth muscle was present in the middle third, while inner and outer layers of smooth muscle were present in the posterior third. Protein gene product 9.5 (PGP 9.5)-, nitric oxide synthase (NOS)-, galanin- and vasoactive intestinal peptide (VIP)-immunoreactive nerve fibers were present in the epithelium, lamina propria, smooth muscle layer and tunica adventitia. In the tunica adventitia, many PGP 9.5- and NOS-immunoreactive neurons were found singly or in small ganglia, while some VIP- and galanin-immunoreactive neurons were observed. A few PGP 9.5- and NOS-immunoreactive neurons were found in the submucosal layer. These results suggest that the trachea of the large flying fox has a rigid structure of tracheal rings and that the posterior two-thirds of the trachea probably contract via the actions of smooth muscles innervated with peptidergic or nitrenergic neurons that are located in tracheal ganglia, whereas the anterior third is non-mobile.     

Structural characterization of interstitial cells of Cajal in myenteric plexus and muscle layers of canine colon

We have carried out a detailed ultrastructural study of the interstitial cells near the myenteric plexus of the canine colon and defined the structural characteristics which distinguish them from other resident non-neural cells. We have also examined the interconnections of these interstitial cells with nerves, the longitudinal muscle, and the circular muscle. In addition, we sought connections between interstitial cells of the myenteric plexus and those described earlier at the inner border of the circular muscle in proximal and distal colon. The interstitial cells of the myenteric plexus were structurally distinctive, and made gap junctions with one another and occasionally with smooth muscle. There seemed to be two subsets of these interstitial cells, one associated with the longitudinal muscle and the other with the circular muscle. Cells of both subsets were often close (less than or equal to 20 nm) to nerve profiles. The interstitial cells near the longitudinal muscle layer penetrated slightly into the muscle layer, but those near the circular muscle did not and neither set contacted the other. Moreover, interstitial cells of Cajal located near the myenteric plexus were never observed to contact those at the inner border of circular muscle. The interstitial cells of Cajal at the canine colon myenteric plexus are structurally organized to provide independent pacemaking activities for the longitudinal and adjacent circular muscle. Their dense innervation suggests that they mediate neural modulation of intestinal pacemaker activities. Moreover, they lack direct contacts with the interstitial cell network at the inner border of circular muscle, which is essential for the primary pacemaking activity of circular muscle. The structural organization of interstitial cells in canine colon is consistent with their proposed role in pacemaking activity of the two muscle layers.     

Ovipositor ultrastructure of the striped bitterling Acheilognathus yamatsutae (Teleostei: Acheilognathinae) during spawning season

The ovipositor of striped bitterling Acheilognathus yamatsutae was subjected to ultrastructure and histochemical analysis during spawning season using light and electron microscopy. Although the ovipositor of A. yamatsutae is a long cylindrical tube with smooth external surface, it was possible to confirm the presence of well-developed fingerprint structure using scanning electron microscopy. Internal aspect analysis of ovipositor revealed formation of 5–8 longitudinal folds. Cross section analysis revealed that the ovipositor is composed of an outer epithelial layer, a mid connective tissue layer, and an inner epithelial layer. The outer epithelial layer contains 7–9 cell layers composed mainly of epithelial and mucous cells. Result of AB–PAS (pH 2.5) and AF–AB reaction showed that mucous cells contained mainly acidic carboxylated mucosubstances. The connective tissue layer was loose and made mainly of collagen fibers and some muscle fibers, along with blood vessels and a small number of chromatophores. The inner epithelial layer, which is a single layer, is composed of columnar epithelia. Observation under transmission electron microscope enabled distinction of the outer epithelial layer into superficial, intermediate and basal layers. Although the types of cells in the superficial tissue layer were diverse, they all shared the development of glycocalyx covered microridges. The majority of epithelial cells in the intermediate layer were cuboidal shaped, while those in the basal layer were columnar. Two types (A and B) of secretory cells were observed in the outer epithelial layer. The connective tissue layer had two types of chromatophores including xantophore and melanophore, in addition to a well-developed nerve fiber bundles. Columnar epithelial cells, mitochondria-rich cells and rodlet cells were observed in the inner epithelial layer. Microvilli were well developed on the free surface of columnar epithelial cells.     

Enteric motor neurons form synaptic-like junctions with interstitial cells of Cajal in the canine gastric antrum

Morphological studies have shown synaptic-like structures between enteric nerve terminals and interstitial cells of Cajal (ICC) in mouse and guinea pig gastrointestinal tracts. Functional studies of mice lacking certain classes of ICC have also suggested that ICC mediate enteric motor neurotransmission. We have performed morphological experiments to determine the relationship between enteric nerves and ICC in the canine gastric antrum with the hypothesis that conservation of morphological features may indicate similar functional roles for ICC in mice and thicker-walled gastrointestinal organs of larger mammals. Four classes of ICC were identified based on anatomical location within the tunica muscularis. ICC in the myenteric plexus region (IC-MY) formed a network of cells that were interconnected to each other and to smooth muscle cells by gap junctions. Intramuscular interstitial cells (IC-IM) were found in muscle bundles of the circular and longitudinal layers. ICC were located along septa (IC-SEP) that separated the circular muscle into bundles and were also located along the submucosal surface of the circular muscle layer (IC-SM). Immunohistochemistry revealed close physical associations between excitatory and inhibitory nerve fibers and ICC. These contacts were synaptic-like with pre- and postjunctional electron-dense regions. Synaptic-like contacts between enteric neurons and smooth muscle cells were never observed. Innervated ICC formed gap junctions with neighboring smooth muscle cells. These data show that ICC in the canine stomach are innervated by enteric neurons and express similar structural features to innervated ICC in the murine GI tract. This morphology implies similar functional roles for ICC in this species.     

Smooth muscle cells, interstitial cells of Cajal and myenteric plexus interrelationships in the human colon

The plane between longitudinal and circular muscle of human colon, as revealed on examination with light and electron microscopes, has no clear-cut border. Some groups of smooth muscle cells, obliquely oriented and with features similar to both circular and longitudinal ones--the connecting muscle bundles--run from one muscle layer to another. Other groups of smooth muscle cells, possessing their own specific ultrastructural features--the myenteric muscle sheaths--, make up envelopes of variable thickness around some myenteric ganglia and nerve strands, partially or completely embedding them in one or other muscle layer. Non-neuronal, non-muscular cells (interstitial cells of Cajal, covering cells, fibroblast-like and macrophage-like cells) complicate the texture of the myenteric muscle sheaths, creating an intricate, interconnected cellular network inside them, widespread among nerve bundles and smooth muscle cells; however, only interstitial cells have cell-to-cell junctions also with the smooth muscle cells and nerve endings. These data document the existence in this colonic area of two different types of muscle cell arrangements, one of which, the myenteric muscle sheath, only contains putative pacemaker cells.     

Origin of galanin in nerves of cat airways and colocalization with vasoactive intestinal peptide

Galanin is a 29 amino acid residue neuropeptide. In mammalian airways, galanin is found in nerve fibers associated with airway smooth muscle, bronchial glands, and blood vessels, and in nerve cell bodies of airway ganglia. The present study was conducted to determine if galanin-containing fibers in the walls of feline airways originate from the nerve cell bodies of airway ganglia. The colocalization of galanin with vasoactive intestinal peptide was also investigated. Organotypic cultures of cat airways were held in culture for 0 (nonculture control), 3, 5, and 7 days. After each culture period, the distribution of galanin and the colocalization of galanin with vasoactive intestinal peptide were determined by immunocytochemistry. Galanin-containing fibers were found in bronchial smooth muscle, around bronchial glands and in the walls of bronchial arteries and arterioles throughout the culture period. Nerve fibers and cell bodies containing both galanin and vasoactive intestinal peptide were observed after all culture periods. Nerve fibers and cells bodies that contained galanin frequently contained vasoactive intestinal peptide as well, but nerve fibers with only galanin or vasoactive intestinal were also observed. Galanin- and vasoactive intestinal peptide-containing nerve fibers and cell bodies were both well maintained throughout the culture period. The findings show that galanin-containing nerve fibers associated with bronchial smooth muscle, bronchial glands, and bronchial arteries, originate from nerve cell bodies of intrinsic airway ganglia, and that galanin and vasoactive intestinal peptide are frequently colocalized in these neurons.     

Neurohormonal peptides, serotonin, and nitric oxide synthase in the enteric nervous system and endocrine cells of the gastrointestinal tract of neotenic and thyroid hormone-treated axolotls (Ambystoma mexicanum)

Immunoreactivity against vasoactive intestinal polypeptide (VIP), neurotensin (NT), substance P (SP), calcitonin gene-related peptide (CGRP), gastrin/cholecystokinin (GAS/CCK), somatostatin (SOM), serotonin (SER), and nitric oxide synthase (NOS) was investigated in the gastrointestinal tract of the urodele Ambystoma mexicanum, the axolotl, by the use of immunohistochemical techniques. The study also compares the distribution patterns and frequencies of the neurohormones, and NOS in neotenic and thyroxine-treated (metamorphosed) individuals. GAS/CCK, SP, NT, SOM, and SER immunoreactivities occurred in endocrine mucosal cells and VIP, SP, CGRP, NTSER, SER, and NOS immunoreactivities in the enteric nervous system. The GAS/CCK-immunoreactive (-IR) cells were restricted to the upper small intestine. NT-IR and SP-IR endocrine cells were found in the entire gastrointestinal tract and were most prominent in the distal large intestine. The density of the SOM-IR cells decreased from the stomach toward the large intestine. SER-IR endocrine cells were found throughout the gastrointestinal tract, with particularly high densities in the stomach and distal large intestine. The VIP-IR enteric nerve fibers were the most prominent ones, present in all layers of the entire gastrointestinal tract, and supplied the smooth muscle and the vasculature. The SER-IR fibers exhibited similar distribution patterns but were less numerous. Very few NT-IR but many SP-IR fibers were found in the muscle and submucosal layers. The NT-IR fibers mainly supplied blood vessels, while the SP-IR fibers were also in contact with the smooth muscle. In the muscle and submucosal layers, CGRP-IR fibers were associated to the vasculature; CGRP immunoreactivity occurred also in a minority of SP-IR fibers. NOS-IR nerve fibers were in contact with submucosal arteries but were the least frequent . After metamorphosis provoked by exogenous thyroxine, the number of SOM-IR endocrine cells in the stomach mucosa was increased as well as the density of VIP-IR, SER-IR, and SP-IR nerve fibers in the gastrointestinal tract. It is proposed that the observed increases may reflect refinements of the neurohormonal system after metamorphosis.     

Neuromuscular structures specific to the submucosal border of the human colonic circular muscle layer

The circular muscle layer of the human caecum and ascending colon is clearly subdivided into two portions: an outer one which includes the bulk of the circular muscle layer, and an inner one made up of only six to eight rows of cells. In the right transverse colon no demarcation can be observed, but a difference exists between the innermost and the outermost cells, since those of the two innermost rows possess some peculiarities with regard to the sarcoplasmic reticulum, glycogen particles, caveolae, and intercellular junctions. In the left part of the colon, the circular muscle layer is also divided into two portions. In fact, the innermost smooth muscle cells still possess peculiar morphologies, progressively increase in number, and become separate from each other making up a superficial muscle network. A fibrous lamella, along and inside which a ganglionated nerve plexus runs, is strictly apposed to the submucosal border of the circular muscle layer of the entire colonic length. A second nerve plexus runs between the two portions of the circular muscle layer. Both these plexuses are accompanied by interstitial cells of Cajal in the right colon only. The peculiar organization of the entire submucosal border of the human colonic circular muscle layer distinguishes it from other parts of the gut and probably represents a structural basis for control of human colonic motility. The presence of putative pacemaker cells (interstitial cells and peculiar smooth muscle cells) indicates that the inner border of human colonic circular muscle layer possesses pacemaking activities. Moreover, the interstitial cell--smooth muscle cell ratio differs depending on the colonic level; two main regions can be identified: the right and the left colon. Consequently, we might expect regional variation in pacemaking.     

人十二指肠血管活性肠肽能P物质能神经分布的研究

本文采用免疫组织化学ＡＢＣ法研究血管活性肠肽（ＶＩＰ） 能神经和Ｐ物质（ＳＰ） 能神经在人十二指肠壁内的分布。结果显示： ＶＩＰ能和ＳＰ能神经纤维和神经元均呈棕褐色; ＶＩＰ能神经纤维遍布肠壁各层,ＳＰ能神经纤维主要分布于肌层和神经丛; ＶＩＰ能和ＳＰ能神经元见于肌间和粘膜下神经, 尤以后者为多, 但形态特点不同; 在肌间神经丛, ＳＰ能神经元比ＶＩＰ能神经元多。粘膜内可见ＶＩＰ能和ＳＰ能神经元, 多单个分布在粘膜肌层内。结果表明： １ＶＩＰ能和ＳＰ能神经在人十二指肠壁内分布有差异。２粘膜内存在ＶＩＰ能和ＳＰ能神经元