A co-localization study on the ovine pancreas innervation

The expression of DbetaH and several neuropeptides was investigated in neuronal elements of the ovine pancreas using double immunocytochemical stainings. Immunoreactivities to DbetaH, NPY, VIP and SP were seen to various extents in nerve terminals associated with the acini, islets, ducts, blood vessels, interlobular connective tissue as well as in the neurons of intrapancreatic ganglia. The expression of CGRP was limited to nerve fibers lying in the connective tissue septa, amongst the acini and in close vicinity to the pancreatic blood vessels. Single GRP-positive nerve endings were located around the acini, ducts and in the interlobular connective tissue. With the exception of the ductal system in a co-localization of NPY with DbetaH was frequently found in all regions of the pancreas. Moderately numerous blood vessel-associated VIP-positive nerve fibers as well as the vast majority of VIP-containing intrapancreatic neurons were found to co-express DbetaH. Single SP-immunoreactive (IR) nerve fibers of the exocrine pancreas and interlobular connective tissue as well as SP-positive intrapancreatic neurons additionally showed the presence of DbetaH. The co-localization of VIP and NPY was found in nerve terminals located around the blood vessels and acini, in the connective tissue septa as well as in numerous pancreatic neuronal perikarya. Rare nerve terminals located between the acini and around small blood vessels as well as several neurons of intrapancreatic ganglia were VIP-IR/ SP-IR. Simultaneous expression of SP and CGRP was found in nerve fibers supplying large pancreatic arteries and veins, interlobular connective tissue and, occasionally, around the acini. Throughout the pancreas the population of CGRP-positive nerve endings showed lack of VIP and NPY. In a moderate number of GRP-containing nerve fibers, a co-expression of NPY was noted. Nerve terminals containing both GRP and VIP were detected sporadically, whereas none of the GRP-positive nerve terminals showed expression of SP. We conclude that the presented noradrenergic as well as peptidergic innervation patterns of the ovine pancreas are species-dependent. On the basis of the occurrence of DbetaH, NPY, VIP and SP (alone or in combination) in pancreatic neuronal elements we can suggest that these substances presumably act as regulators of the endocrine and/or exocrine pancreas. Involvement of CGRP and GRP in the ovine pancreas physiology seems to be of minor importance. The co-localization study indicated that the pancreas of the sheep is innervated from several sources including intrinsic as well as extrinsic ganglia.     

An electron microscopic study of acetylcholinesterase-activity and vasoactive intestinal peptide- and neuro-peptide Y-immunoreactivity of the intraepithelial nerve fibers in the nasal gland of the guinea pig

In combination with transmission electron microscopy (TEM), histochemistry for acetylcholinesterase (AChE) and immunohistochemistry for vasoactive intestinal peptide (VIP) and neuropeptide Y (NPY) were carried out on the intraepithelial nerve fibers of the guinea-pig nasal gland. AChE-positive nerve profiles and VIP-immunoreactive nerve profiles were detected in abundance within the epithelium of the glandular acini and within the epithelium of intralobular excretory ducts including the intercalated and striated ducts. Intraepithelial NPY-immunoreactive nerve profiles were also considerably large in number in the nasal gland, but less frequent than the other two types of nerve profiles; furthermore, the NPY-immunoreactive nerve profiles appeared absent within the epithelium of the striated duct. All the intraepithelial nerve varicosities were in close spatial contact with the epithelial cells of the acinus and the duct and also with the myoepithelial cells, which were commonly seen in the acinus and the intercalated duct. Throughout the present study, however, no membranous specializations could be found between the nerve varicosities and the epithelial cells or the myoepithelial cells. The present results suggest an intense and delicate regulation through the collaboration among ACh, VIP and NPY of the secretory activity of the guinea-pig nasal gland, including the emission of acinar secretions into the duct through contraction of the myoepithelium and modification of the secretion contents by the duct epithelium.     

Vasoactive intestinal polypeptide (VIP) immunoreactivity in the ependymal cells of the rat spinal cord

Vasoactive intestinal polypeptide (VIP) was demonstrated immunohistochemically in the entire ependymal and subependymal cells in all levels (cervical: C, thoracic: T, lumbar: L and sacral: S) of normal adult rat spinal cord. The VIP-immunoreactive basal processes from the apical ependymal cells coursed dorsally or ventrally along the median plane and reached the pia mater of the dorsal and ventral median septa. Many VIP-immunoreactive basal processes terminated on the blood vessels in the neuropil around the central canal. A few microvilli of the ependymal cells that project into the central canal also demonstrated intense VIP immunoreactivity. These observations suggest that ependymal cells may be involved in the modulation of VIP levels in the cerebrospinal fluid and regulation of vascular tone of the blood vessels in the spinal cord.     

Vasoactive intestinal polypeptide-immunoreactive nerves in the kidney

Nerve fibers immunoreactive for vasoactive intestinal polypeptide (VIP) were demonstrated by immunocytochemistry in the dog and rat kidney. They were seen in association with the renal artery and its branches. In the dog, VIP-immunoreactive fibers were rarely seen close to small blood vessels suggestive of arterioles. The possible existence of neuroeffector junctions between VIP-positive fibers and renin-secreting juxtaglomerular cells requires further investigation. VIP-positive renal nerves, however, might have a vasodilatatory role.     

Morphological evidence of sensory neurons in the root of the rat tongue

In our previous studies, a large number of substance P (SP)-immunoreactive (IR) nerve fibers were detected in the rat tongue and their number increased after inflammation, suggesting that these fibers might be involved in the axon reflex. Therefore, in this study, we have examined the different neuropeptide-containing nerve elements by light, electron, and confocal laser microscopy. SP, vasoactive intestinal polypeptide (VIP), and neuropeptide Y (NPY) IR varicose fibers were numerous compared with other ones. Small groups of ganglia with perikarya IR for SP, VIP, NPY, galanin, and somatostatin were observed. The SP-IR nerve cell bodies were mainly located in the tunica propria just below the epithelial lining. Double-labeling immunohistochemistry showed that the intrinsic SP-IR neurons did not colocalize VIP. The SP containing nerve terminals were observed in and below the epithelium as well as in very close contact to or making real synapses with other neurons in the intralingual ganglion. Our data confirmed the possibility of intrinsic sensory neurons, which might be the afferent branch of the intralingual reflex arch, while the VIP- and NPY-IR neurons located in the salivary glands, around the blood vessels, and in the muscle layer might constitute the efferent site of this reflex.     

Ultrastructural localization of VIP-like immunoreactivity in large dense-core vesicles of ‘cholinergic-type’ nerve terminals in cat exocrine glands

Exocrine glands of the cat were analysed with the peroxidase-antiperoxidase method and routine electron microscopy. Vasoactive intestinal polypeptide (VIP)-like immunoreactivity was observed in certain nerve endings in the submandibular salivary gland, lacrimal gland and Harderian gland. The distribution of the VIP immunoreactive nerve fibres agreed well with earlier light microscopic findings. At the electron microscopic level electron-dense precipitates representing VIP-like immunoreactivity were seen in so-called large dense-core vesicles (median diameter about 990A?) in nerve fibres and varicosities also containing many small (‘immunonegative’) agranular vesicles. In conventional electron microscopy, the small agranular vesicles outnumbered the large dense-core vesicles by about 9 to 1. Immunoreactive fibres and varicosities could be seen close to the secretory acini (distance less than 400A?) and more distant (1500A?or more) to e.g. demilunes, ducts and blood vessels of the glands. The number and distribution of immunoreactive nerve fibres were not affected by sympathectomy. Furthermore, no typical ‘p-type’ bouton profiles, which are dominated by large opaque vesicles (dia. 800–2000A?), could be seen in the ultrastructural analysis of conventional preparations of the glands.The morphological features of the VIP immunoreactive nerve endings could not be distinguished from those often described as representing cholinergic fibres. These findings are in agreement with earlier suggestions of a possible coexistence of acetylcholine and VIP in neurons innervating exocrine glands and indicate possible functions for VIP in the roles of these nerves in evoking vasodilation and exocrine secretion.     

VIP neurons as prime synaptic targets for serotonin afferents in rat suprachiasmatic nucleus: a combined radioautographic and immunocytochemical study

Summary Cellular relationships between serotonin (5-HT) axon terminals and neurons containing vasoactive intestinal peptide (VIP) were characterized by combined radioautography and immunocytochemistry in rat suprachiasmatic nucleus (SCN). Light microscopic immunoradioautographs showed significant overlap between (³H)5-HT uptake sites and VIP-immunoreactive elements in the ventral half of the SCN. Of the 255 (³H)5-HT-labelled axonal profiles detected in a systematic electron microscopic survey of single thin sections from this area, 75 (30%) were directly apposed to VIP-immunoreactive nerve cell bodies and/or dendrites. Radioautographically labelled 5-HT varicosities often showed well-differentiated, symmetrical or asymmetrical synaptic junctions, 60% of which were established on VIP-immunoreactive nerve cell bodies or dendrites. In a separate sampling of 198 (³H)5-HT-labelled terminals seen in apposition with VIP-immunoreactive elements, 50 showed a junctional complex at the site of contact. Postsynaptic immunoreactive elements were mostly dendrites but also included nerve cell bodies. Despite the methodological limitations inherent to the present double labelling approach, these data strongly support the view that VIP neurons are prime synaptic targets for 5-HT afferents in the SCN. VIP/5-HT interactions are thus likely to play an important functional role in this nucleus and may in particular subserve the 5-HT mediated regulation of certain circadian rhythms, including that of pituitary hormone secretion.     

扬子鳄卵巢内血管活性肠肽、神经肽Y和P物质的分布

目的:观察扬子鳄卵巢内血管活性肠肽（vasoactive　intestinal　peptide,VIP）、神经肽Y（neuropeptide Y,NPY）和P物质（substance P,SP）的分布情况。方法:免疫荧光法。结果:扬子鳄卵巢内的VIP免疫反应（VIP-immunoreac-tive,VIP-IR）阳性神经纤维呈波浪状,部分包绕卵泡,大部分交织在卵泡间血管周围,并构成较密集的网络;SP和NPY免疫反应（SP-and NPY-immunoreactive,SP-和NPY-IR）阳性神经纤维均为点线状,主要沿卵泡间血管周围分布,其中,部分NPY-IR纤维也构成较密集的网络。切片中均未见到三种肽能神经元的细胞体。结论:扬子鳄卵巢内存在有VIP、NPY和SP阳性神经纤维分布,主要位于卵泡间血管周围。     

Sensory innervation of the Achilles tendon by group III and IV afferent fibers

Summary In sympathectomized cats the innervation of the Achilles tendon by fine afferent nerve fibers was studied with semithin and ultrathin sections. Several different types of sensory endings of group III and group IV nerve fibers were identified.Of the five different types of endings in the group III range (T III endings), two are located within vessel walls. One of them ends in the circumference of the venous vessels (T III/VV). Its lanceolate terminals have characteristic receptor areas at their edges. The second type ends in the adventitia of lymphatic vessels (T III/LV). Its receptive areas are scattered along their terminal course. Two further group III endings ramify within the connective tissue compartments of the vessel-nerve-fascicles of the peritenonium externum and internum. One type is tightly surrounded by collagen fibrils (T III/PTic); the other terminates between the collagen fiber bundles (T III/PTgc). The latter arrangement recalls the ultrastructural relation between nerve terminals and collagen tissue in Golgi tendon organs.The fifth type innervates the endoneural connective tissue of small nerve fiber bundles (T III/EN). At least some of them come into close contact with bundles of collagen fibers which penetrate the perineural sheath to terminate within the endoneurium.The endings of group IV afferents (T IV endings) show a striking topographic relationship to the blood and lymphatic vessels of all connective tissue compartments of the Achilles tendon. They form penicillate endings which may contain granulated vesicles. In any event, they can easily be discriminated from the T III endings in the vessel walls.In close neighborhood to Remak bundles, a cell has been regularly found which fulfilled all ultrastructural criteria for mast cells. But this cell is not a mast cell proper because it is surrounded by a basal lamina (pseudo mast cell).     

The distribution of acetylcholinesterase(AChE)-positive nerves in chicken pancreas demonstrated by light and electron microscopy

The distribution of acetylcholinesterase (AChE)-positive nerve fibers in the chicken pancreas was investigated with histochemical methods at the light and electron microscopic level. AChE-positive nerve bundles were found to run along the pancreaticoduodenal artery and their branches proceed into interlobular connective tissue, form a plexus around the interlobular secretory ducts and small arteries, and penetrate the exocrine parenchyma. Intrapancreatic ganglia showing a strong AChE activity were detected within the interlobular connective tissue or between acini. The exocrine pancreas was richly innervated with AChE-positive terminals which contained a few large dense-cored vesicles (about 100 nm in diameter) and many small clear vesicles (about 50 nm in diameter). Such terminals made contact with intercalated ductular cells and the smooth muscles of larger blood vessels. The endocrine pancreas was supplied with fewer nerves than the exocrine pancreas. A different distribution of AChE-positive fibers was noticed between A- and B-islets which were distinguished immunohistochemically. B- and D-cells were richly innervated by AChE-positive nerves, whereas A-cells, only poorly. These observations make clear that the cholinergic system relates to the regulation of both exocrine and endocrine tissues, except A-cells, in the chicken pancreas.     

Expression and distribution of GABA and GABAB‐receptor in the rat adrenal gland

The inhibitory effects of gamma‐aminobutyric acid (GABA) in the central and peripheral nervous systems and the endocrine system are mediated by two different GABA receptors: GABA_A‐receptor (GABA_A‐R) and GABA_B‐receptor (GABA_B‐R). GABA_A‐R, but not GABA_B‐R, has been observed in the rat adrenal gland, where GABA is known to be released. This study sought to determine whether both GABA and GABA_B‐R are present in the endocrine and neuronal elements of the rat adrenal gland, and to investigate whether GABA_B‐R may play a role in mediating the effects of GABA in secretory activity of these cells. GABA‐immunoreactive nerve fibers were observed in the superficial cortex. Some GABA‐immunoreactive nerve fibers were found to be associated with blood vessels. Double‐immunostaining revealed GABA‐immunoreactive nerve fibers in the cortex were choline acetyltransferase (ChAT)‐immunonegative. Some GABA‐immunoreactive nerve fibers ran through the cortex toward the medulla. In the medulla, GABA‐immunoreactivity was seen in some large ganglion cells, but not in the chromaffin cells. Double‐immunostaining also showed GABA‐immunoreactive ganglion cells were nitric oxide synthase (NOS)‐immunopositive. However, neither immunohistochemistry combined with fluorescent microscopy nor double‐immunostaining revealed GABA‐immunoreactivity in the noradrenaline cells with blue‐white fluorescence or in the adrenaline cells with phenylethanolamine N‐methyltransferase (PNMT)‐immunoreactivity. Furthermore, GABA‐immunoreactive nerve fibers were observed in close contact with ganglion cells, but not chromaffin cells. Double‐immunostaining also showed that the GABA‐immunoreactive nerve fibers were in close contact with NOS‐ or neuropeptide tyrosine (NPY)‐immunoreactive ganglion cells. A few of the GABA‐immunoreactive nerve fibers were ChAT‐immunopositive, while most of the GABA‐immunoreactive nerve fibers were ChAT‐immunonegative. Numerous ChAT‐immunoreactive nerve fibers were observed in close contact with the ganglion cells and chromaffin cells in the medulla. The GABA_B‐R‐immunoreactivity was found only in ganglion cells in the medulla and not at all in the cortex. Immunohistochemistry combined with fluorescent microscopy and double‐immunostaining showed no GABA_B‐R‐immunoreactivity in noradrenaline cells with blue‐white fluorescence or in adrenaline cells with PNMT‐immunoreactivity. These immunoreactive ganglion cells were NOS‐ or NPY‐immunopositive on double‐immunostaining. These findings suggest that GABA from the intra‐adrenal nerve fibers may have an inhibitory effect on the secretory activity of ganglion cells and cortical cells, and on the motility of blood vessels in the rat adrenal gland, mediated by GABA‐Rs.     

Ontogeny of the VIP system in the gastro-intestinal tract of the Axolotl,Ambystoma mexicanum: successive appearance of co-existing PACAP and NOS

Evidence for the presence and potential co-existence of vasoactive intestinal polypeptide (VIP), pituitary adenylate cyclase-activating polypeptide (PACAP) and nitric oxide synthase (NOS) in gastro-intestinal endocrine cells and/or nerve fibers is conflicting and very few results exist on development. This immunofluorescence study aims to clarify the appearance and localization of VIP, PACAP and NOS in the gastro-intestinal tract of the Axolotl, Ambystoma mexicanum, during ontogeny. VIP-immunoreactivity appeared in nerve fibers as early as on day 3 after hatching likely indicating a particular role, such as a trophic action, of VIP in very early development. PACAP-immunoreactivity was observed 3 days later within the VIP-immunoreactive (-IR) fibers. From this time on, VIP- and PACAP-immunoreactivity exhibited complete co-existence. VIP/PACAP-IR fibers were found throughout the gastro-intestinal tract. They were most prominent in the myenteric plexus and the muscle layers and less frequent in the submucosa. NOS-immunoreactivity appeared as late as at the 1st (64 days) juvenile stage in a subpopulation of the VIP/PACAP-IR fibers that contacted submucosal arteries. We found only very few VIP/PACAP-IR perikarya, indicating that part of the VIP/PACAP-IR fibers is of extrinsic origin. On day 12 and in the 1st and 2nd (104 days) juvenile stage, infrequent PACAP-IR entero-endocrine cells were noted, while neither VIP- nor NOS-immunoreactivity occurred in endocrine cells at any stage of development. The complete coexistence of neuronal PACAP- and VIP-immunoreactivities and their very early appearance in ontogeny may suggest important and coordinated roles of both peptides in the control of Axolotl gastro-intestinal activity, while the VIP/ PACAP/NOS-IR fibers may be involved in the regulation of submucosal blood flow.     

Ontogeny of the VIP system in the gastro-intestinal tract of the Axolotl,<Emphasis Type="Italic"> Ambystoma mexicanum</Emphasis>: successive appearance of co-existing PACAP and NOS

Evidence for the presence and potential co-existence of vasoactive intestinal polypeptide (VIP), pituitary adenylate cyclase-activating polypeptide (PACAP) and nitric oxide synthase (NOS) in gastro-intestinal endocrine cells and/or nerve fibers is conflicting and very few results exist on development. This immunofluorescence study aims to clarify the appearance and localization of VIP, PACAP and NOS in the gastro-intestinal tract of the Axolotl, Ambystoma mexicanum, during ontogeny. VIP-immunoreactivity appeared in nerve fibers as early as on day 3 after hatching likely indicating a particular role, such as a trophic action, of VIP in very early development. PACAP-immunoreactivity was observed 3 days later within the VIP-immunoreactive (-IR) fibers. From this time on, VIP- and PACAP-immunoreactivity exhibited complete co-existence. VIP/PACAP-IR fibers were found throughout the gastro-intestinal tract. They were most prominent in the myenteric plexus and the muscle layers and less frequent in the submucosa. NOS-immunoreactivity appeared as late as at the 1st (64 days) juvenile stage in a subpopulation of the VIP/PACAP-IR fibers that contacted submucosal arteries. We found only very few VIP/PACAP-IR perikarya, indicating that part of the VIP/PACAP-IR fibers is of extrinsic origin. On day 12 and in the 1st and 2nd (104 days) juvenile stage, infrequent PACAP-IR entero-endocrine cells were noted, while neither VIP- nor NOS-immunoreactivity occurred in endocrine cells at any stage of development. The complete coexistence of neuronal PACAP- and VIP-immunoreactivities and their very early appearance in ontogeny may suggest important and coordinated roles of both peptides in the control of Axolotl gastro-intestinal activity, while the VIP/ PACAP/NOS-IR fibers may be involved in the regulation of submucosal blood flow.     

扬子鳄大肠和输尿管的神经肽分布

目的:观察扬子鳄大肠的神经肽Y（neuropeptide Y,NPY）、血管活性肠肽（vasoactive intestinal peptide,VIP）和输尿管的P物质（substance P,SP）、血管活性肠肽分布。方法:免疫荧光方法。结果:扬子鳄大肠的NPY和VIP免疫反应（NPY-and VIP-immunoreactive,NPY和VIP-IR）阳性神经纤维皆呈弯曲的细线状,主要位于粘膜下层,其次为浅部肌层,且在粘膜下层NPY-IR神经纤维交织成密集的神经丛;VIP-IR神经纡维在粘膜下层构成稀疏的网络状。输尿管的SP免疫反应（SP-immunoreactive,SP-IR）和VIP-IR神经纤维均呈点线状;其中,SP-IR神经纤维位于外膜层,较稀疏,VIP-IR神经纤维位于肌层,较密集,纤维间可见两个近似圆形的VIP-IR阳性神经细胞体。结论:扬子鳄大肠和输尿管分别存在有NPY、VIP和SP、VIP神经分布。     

Mucosal nerves and smooth muscle relationships with gastric glands of the opossum: An ultrastructural and three-dimensional reconstruction study

The precise anatomical relation by which autonomic nerve endings contact gastric epithelial cells to enhance the rate of gastric secretions is not fully understood. The aim of the present study was to clarify this issue by using the technique of serial section reconstruction of areas of the gastric mucosa. The work also explored the possibility of a functional role for a system of smooth muscle strands in the gastric mucosa that emanate from the muscularis mucosa, run in the lamina propria, and are associated in a unique manner with the gastric glands. Electron microscopic serial sections of the gastric mucosa were performed to visualize the entire limiting membrane of gastric epithelial cells to determine any nerve associations (especially varicose endings) with these cells. Evaluation of serial sections of five separate parietal cells showed that their basal membrane did not come in close contact (nearest distance 500 nm) with any nerve axon or varicosity. Moreover, the axons passing in the area of these cells ultimately showed varicose endings associated with smooth muscle cells in the adjacent connective tissue (often separated by only 20 nm), with mast cells or with vascular elements. Additionally, the lateral membrane of these five parietal cells did not contact any endocrine cell in the epithelium, although other parietal cells in the area were adjacent to endocrine cells. Chief cells in the immediate area also did not form any close associations with nerve varicosities. Random analysis of 5,000 additional epithelial cells in these sections showed no close associations to nerve elements with significant accumulations of neurosecretory vesicles (varicosities). Because of the observed existence of innervation to the smooth muscle strands in the area of the gastric glands, serial 1-μm epoxy sections of the gastric mucosa were prepared, and profiles of smooth muscle and gastric glands were entered into a computer-assisted reconstruction system. Three-dimensional reconstruction techniques were employed to reveal the existence of a unique association between the mucosal smooth muscle strands and the gastric glands. The muscle strands arose from the muscularis mucosa at regular intervals and became branched to form an intricate wrap around a series of gastric glands that empty into one gastric pit. Branching of the muscle strands initially occurred at the point where they approached the base of the glands and then emanated into the connective tissue around the glands in a crossing pattern, ending at the base of the gastric pit. Although muscarinic agents have been shown to directly stimulate parietal cells to secrete acid, these findings have led us to postulate that autonomic nerve stimulation may also aid gastric secretion both by stimulation of mast cells and by glandular excretion mediated via mucosal muscular contractions.     

Light- and electron-microscopic immunocytochemistry of glutamic acid decarboxylase (GAD) in the basal hypothalamus: Morphological evidence for neuroendocrine γ -aminobutyrate (GABA)

GABAergic cells and axon terminals were localized in the basal hypothalamus of different species (rat, mouse and cat), by means of an immunocytochemical approach using a specific and well-characterized antiserum to the GABA biosynthetic enzyme, glutamate decarboxylase. Lightmicroscopic visualization was performed with an indirect immunofluorescence method and electron-microscopic observations were made on material with pre-embedding staining and use of the peroxidase-antiperoxidase procedure.At the light-microscopic level, a dense immunofluorescent plexus was observed over both the medial and lateral parts of the external layer of the median eminence. The labelling extended from the rostral part of the median eminence up to the pituitary stalk. Over the subependymal and internal layers only a few immunoreactive dots were visible, except around the blood vessels where they appeared more concentrated. Immunoreactive varicosities could be found following the outlines of the capillary loops and lining tanycyte processes, especially in the median eminance midportion.At the electron-microscopic level, the immunolabelling was exclusively found over neuronal profiles in the median eminence. The latter represented a small fraction of the total number of varicosities visible on the same section. Labelled profiles typically contained numerous small clear synaptic vesicles and only a few or no dense-core vesicles. In the subependymal and internal layers, rare labelled endings were found close to ependymal cells or among transversally cut fibers, respectively. In the palisadic zone, elongated positive boutons were visible intermingled with bundles of unlabelled axons and glial or ependymal processes. In the neurohemal contact zone, immunoreactive endings were observed among unlabelled neurosecretory endings in close vicinity to fenestrated capillary perivascular space.Small moderately intense immunofluorescent varicosities were observed all over the hypothalamus. The density of the glutamate decarboxylase-positive network was higher than in most diencephalic regions. Intraventricular or topical injection of colchicine allowed the visualization of small lightly immunoreactive cells in the diffusion area of colchicine. In the arcuate nucleus labelled axonal endings containing small pleomorphic synaptic vesicles and sometimes a few dense-core vesicles were observed at the electron-microscopic level. Typical synaptic junctions were commonly found between positive endings and unlabelled perikarya, or more frequently, unlabelled dendrites.These findings show that glutamate decarboxylase-containing endings are localized in several strategic sites for potential GABAergic neuroendocrine regulations. The GABAergic endings found among neurosecretory endings in the neurohemal contact zone may provide the morphological support for the release of γ -aminobutyrate into the portal blood flow as an hypothalamic hypophysiotropic hormone. Alternatively, neurosecretory cells might be under GABAergic control expressed either at their terminal level within the median eminence or the cell body level within the parvicellular hypothalamic nuclei.     

Innervation of human adrenal gland and adrenal cortical lesions

The innervation of the human adrenal gland and of cortical lesions was studied in sections of cortical tissue (n=10), hyperplastic cortical tissue (n=3), and tissue from cortical adenomas (n=5) and carcinomas (n=6). The presence and distribution of nerve structures containing neuronal markers indicating sympathetic and parasympathetic innervation were studied by immunohistochemistry and the co-existence and co-localization patterns of the different markers by immunofluorescence. The cortex and hyperplastic cortical tissue had a moderate to rich supply of nerve structures containing the typical neuronal markers: protein gene product 9.5 (PGP 9.5), neuron-specific enolase (NSE), small vesicle synaptic protein type 2 (SV2), and nerves showing immunoreactivity to the adrenergic marker tyrosine hydroxylase (TH). All these immunoreactive nerves were located predominantly adjacent to blood vessels, but also among parenchymal cells. The cortex showed numerous nerve structures containing the neuropeptide substance P (SP), neuropeptide Y (NPY) and vasoactive intestinal protein (VIP), but few nerves containing these peptides were seen in hyperplastic cortical tissue. Typical markers were occasionally observed in cortical adenomas but were not found in carcinomas, except in a few cases where PGP 9.5 and NSE were present, but only adjacent to necrotic areas. Nerves containing NPY and VIP occurred in varying numbers in both adenomas and carcinomas. NPY- and VIP-immunoreactive nerve structures were seen mostly alongside blood vessels. There were several types of co-existence. For instance, NSE/VIP-, TH/VIP- and TH/NPY-immunoreactive nerve structures were often seen in the same trunk, but were only partly co-localized. Received: 19 January 1999 / Accepted: 18 May 1999     

Perivascular nerves with immunoreactivity to vasoactive intestinal polypeptide in cephalic arteries of the cat: distribution, possible origins and functional implications

The distribution of nerves containing vasoactive intestinal polypeptide(VIP)-immunoreactive material was examined in the cephalic arteries and cranial nerves of cats using an indirect immunofluorescence procedure on whole mounts. Perivascular VIP-immunoreactive nerves were widely distributed in arteries and arterioles supplying glands, muscles and mucous membranes of the face. Within the cerebral circulation, perivascular VIP-immunoreactive nerves were most abundant in the circle of Willis and the proximal portions of the major cerebral arteries and their proximal branches supplying the rostral brainstem and ventral areas of the cerebral cortex. Nerves containing VIP-immunoreactive material were absent from distal portions of arteries supplying the posterior brainstem, cerebellum and dorsal cerebral cortex. Cerebral perivascular VIP-immunoreactive nerves had extracerebral origins probably from VIP-immunoreactive perikarya within microganglia in the cavernous plexus and external rete. Extracerebral perivascular VIP-immunoreactive nerves probably arose from VIP-immunoreactive perikarya in microganglia associated with the tympanic plexus, chorda tympani, lingual nerve and Vidian nerve as well as from cells in the otic, sphenopalatine, submandibular and sublingual ganglia. Therefore, it seems likely that each major segment of the cephalic circulation is supplied by local VIP-immunoreactive neurons. If the VIP-immunoreactive nerves cause vasodilation, they are well placed to allow redistribution of arterial blood flow within the head. During heat stress, neurogenic vasodilation of the appropriate beds would permit efficient cooling of cerebral blood, particularly that supplying the rostral brainstem and surrounding areas of the cerebral cortex.     

On the sensitive innervation of the ostrich's foot pads

The sensitive and autonomic innervation of foot pads in the ostrich was studied employing an usual histological technique as hematoxylin-eosin or different gold chloride impregnations. The autonomic innervation is represented by isolated or grouped ganglion cells located along the course of nerve bundles. The sensitive somatic innervation is composed by free and capsulated nerve endings usually distributed in the thickness of the connective arrangement of the foot pads, in the most superficial part the first one, while the latter was generally located close to the blood vessels. The capsulated nerve endings, morphologically classified as Pacini, Pacini-like and Herbst corpuscles, show the typical structure. They are not uniformly distributed throughout the considered districts and their number are always higher in the plantar pad compared with digital pads. These corpuscles could be found isolated or assembled to organize simple flower-sprays and to constitute opposito-polar corpuscles. The Authors have put forward a hypothesis on the possible functional role of the above-mentioned nerve components.