Acetylcholinesterase-positive Nerve Fibers Research Articles

Organic secretion in ductal cells of the sublingual salivary gland of ferret: Histochemical observations

The presence of organic secretion in ductal cells of the sublingual salivary gland of ferret has been questioned, which prompted the present investigation. Paraffin or cryostat sections from aldehyde fixed or quenched sublingual glands of this species were tested for some amino acid residues, mucosubstances, oxidative and hydrolytic enzymes, and lectins. The glands showed inconspicuous ducts of simple appearances on routine histology. The histochemical procedures, however, revealed a granulated substance in the apical (periluminal) region of ductal cells, which contained tryptophan, disulphides, neutral mucosubstances, αFuc and GalNAc, and showed chloroacetate esterase activity. Occurrence of the substance varied between different ducts of the same gland and/or cells of the same duct. The ductal cells also showed diffuse peroxidase and acid phosphatase, and Golgi-like thiamine pyrophosphatase activities. Acetylcholinesterase-positive nerve fibres embraced the ducts. The results support a particular localisation of protein-bound amino acid residues and enzymatic catalytic activities indicative of organic secretion, possibly tissue kallikrein, in sublingual ductal cells of ferret.

Engineered bone marrow-derived cell sheets restore structure and function of radiation-injured rat urinary bladders.

Previously, we reported that implantation of isolated single bone marrow-derived cells into radiation-injured urinary bladders could restore structure and function. However, injections of isolated single cells had some limitations. Thus, in this study, we produced bone marrow-derived cell sheets in temperature-responsive culture dishes that release the monolayer sheets intact. We then determined whether the produced cell sheets could restore function to irradiated urinary bladders. Twenty female 10-week-old Sprague-Dawley (SD) rats were irradiated with 2 gray once a week for 5 weeks. Bone marrow cells harvested from two male 17-week-old green fluorescence protein-transfected SD rats were placed in primary culture for 7 days. Bone marrow cell-derived outgrowths were harvested by enzymatic digestion and transferred into the atelocollagen-coated temperature-responsive culture dishes for 2 days. To harvest the secondarily cultured cells as monolayer sheets, a support membrane was put in each culture dish, and then the temperature was reduced to 20°C. Each released cell sheet was then patched onto the irradiated anterior bladder wall (n=10). As controls, cell-free sheets were similarly patched (n=10). After 4 weeks, transplanted cells were detected on the bladder walls. The cell sheet-transplanted bladders had smooth muscle layers and acetylcholinesterase-positive nerve fibers in proportions that were significantly larger than those of the control bladders. In addition, the cell sheet-transplanted bladders had reduced prolyl 4-hydroxylase beta (P4HB)-positive regions of collagen synthesis and apoptosis within the smooth muscle layers. In cystometric investigations, threshold pressures, voiding interval, micturition volume, and bladder capacity in the cell sheet-transplantation group were significantly higher than those in the control group. Residual volume of the cell sheet-transplantation group was significantly lower compared with the control. There were 24 growth factor mRNAs in the cell sheet-transplanted urinary bladders that were expressed greater than or equal to two-fold over the controls. In conclusion, cell sheet engineering has great potential to restore damaged urinary bladders.

Cholinergic innervation of human mesenteric lymphatic vessels

The cholinergic neurotransmission within the human mesenteric lymphatic vessels has been poorly studied. Therefore, our aim is to analyse the cholinergic nerve fibres of lymphatic vessels using the traditional enzymatic techniques of staining, plus the biochemical modifications of acetylcholinesterase (AChE) activity. Specimens obtained from human mesenteric lymphatic vessels were subjected to the following experimental procedures: 1) drawing, cutting and staining of tissues; 2) staining of total nerve fibres; 3) enzymatic staining of cholinergic nerve fibres; 4) homogenisation of tissues; 5) biochemical amount of proteins; 6) biochemical amount of AChE activity; 6) quantitative analysis of images; 7) statistical analysis of data. The mesenteric lymphatic vessels show many AChE positive nerve fibres around their wall with an almost plexiform distribution. The incubation time was performed at 1 h (partial activity) and 6 h (total activity). Moreover, biochemical dosage of the same enzymatic activity confirms the results obtained with morphological methods. The homogenates of the studied tissues contain strong AChE activity. In our study, the lymphatic vessels appeared to contain few cholinergic nerve fibres. Therefore, it is expected that perivascular nerve stimulation stimulates cholinergic nerves innervating the mesenteric arteries to release the neurotransmitter AChE, which activates muscarinic or nicotinic receptors to modulate adrenergic neurotransmission. These results strongly suggest, that perivascular cholinergic nerves have little or no effect on the adrenergic nerve function in mesenteric arteries. The cholinergic nerves innervating mesenteric arteries do not mediate direct vascular responses.

Repair of sciatic nerve defects using tissue engineered nerves.

In this study, we constructed tissue-engineered nerves with acellular nerve allografts in Sprague-Dawley rats, which were prepared using chemical detergents-enzymatic digestion and mechanical methods, in combination with bone marrow mesenchymal stem cells of Wistar rats cultured in vitro, to repair 15 mm sciatic bone defects in Wistar rats. At postoperative 12 weeks, electrophysiological detection results showed that the conduction velocity of regenerated nerve after repair with tissue-engineered nerves was similar to that after autologous nerve grafting, and was higher than that after repair with acellular nerve allografts. Immunohistochemical staining revealed that motor endplates with acetylcholinesterase-positive nerve fibers were orderly arranged in the middle and superior parts of the gastrocnemius muscle; regenerated nerve tracts and sprouted branches were connected with motor endplates, as shown by acetylcholinesterase histochemistry combined with silver staining. The wet weight ratio of the tibialis anterior muscle at the affected contralateral hind limb was similar to the sciatic nerve after repair with autologous nerve grafts, and higher than that after repair with acellular nerve allografts. The hind limb motor function at the affected side was significantly improved, indicating that acellular nerve allografts combined with bone marrow mesenchymal stem cell bridging could promote functional recovery of rats with sciatic nerve defects.

Total Colonic Aganglionosis: Case Report, Practical Diagnostic Approach and Pitfalls

Hirschsprung disease remains a challenging diagnosis for many pathologists. The disease is characterized by a lack of ganglion cells in the myenteric and submucosal plexus, associated with increased numbers of acetylcholinesterase-positive nerve fibers. Hypertrophic nerve fibers are present in most but not all patients. Total colonic aganglionosis (TCA) is an uncommon form of Hirschsprung disease with clinical, histologic, and genetic differences and is even more difficult to diagnose and manage. This case illustrates some of the difficulties frequently faced by the pathologists dealing with total colonic aganglionosis. Suction rectal biopsy specimens often lack significant nerve hypertrophy and positive acetylcholinesterase staining, which aid in the diagnosis. Pathologists have to depend mainly on the lack of ganglion cells in adequate submucosa to establish the diagnosis. Transition zone is often long in total colonic aganglionosis and interpretation of frozen sections can be difficult. The presence of several uniformly distributed clusters of mature ganglion cells and lack of nerve hypertrophy are required to avoid connections at the transition zone.

Total colonic aganglionosis: case report, practical diagnostic approach and pitfalls.

Hirschsprung disease remains a challenging diagnosis for many pathologists. The disease is characterized by a lack of ganglion cells in the myenteric and submucosal plexus, associated with increased numbers of acetylcholinesterase-positive nerve fibers. Hypertrophic nerve fibers are present in most but not all patients. Total colonic aganglionosis (TCA) is an uncommon form of Hirschsprung disease with clinical, histologic, and genetic differences and is even more difficult to diagnose and manage. This case illustrates some of the difficulties frequently faced by the pathologists dealing with total colonic aganglionosis. Suction rectal biopsy specimens often lack significant nerve hypertrophy and positive acetylcholinesterase staining, which aid in the diagnosis. Pathologists have to depend mainly on the lack of ganglion cells in adequate submucosa to establish the diagnosis. Transition zone is often long in total colonic aganglionosis and interpretation of frozen sections can be difficult. The presence of several uniformly distributed clusters of mature ganglion cells and lack of nerve hypertrophy are required to avoid connections at the transition zone.

Extracts obtained from predegenerated nerves improve functional recovery after sciatic nerve transection

Gap injuries of peripheral nerves, resulting from trauma or neurosurgical procedures, presage badly, for the presence of the distal stump of the nerve seems to be indispensable for regeneration. The standard grafting method requires a lesion of a healthy nerve, and therefore various substitutional materials are under consideration. The aim of the present work was to examine the recovery of rat sciatic nerves after supplying 10-mm-long gaps with an autologous connective-tissue chambers filled with fibrin only or fibrin and various neuroactive substances (brain-derived neurotrophic factor (BDNF), extracts from predegenerated or non-predegenerated nerves). The nerves were allowed to regenerate for 16 weeks. Recovery was measured functionally using the sciatic functional index, and by comparing the weight ratios of calf muscles. The histologic features of regeneration were assessed by counting the number of acetylcholinesterase-positive nerve fibers present inside implanted chambers. We found that chambers filled with fibrin and predegenerated peripheral nerve extracts or BDNF supported functional nerve regeneration much more strongly than chambers filled with fibrin only or fibrin and non-predegenerated peripheral nerve extracts. We conclude that autologous connective-tissue chambers filled with fibrin and predegenerated peripheral nerve extracts or BDNF seem to be a promising tool in peripheral nerve gap injury treatment, with likely clinical implications.

Innervation of congenitally hydronephrotic and normal porcine upper urinary tract.

To investigate the intrinsic innervation of the upper urinary tract in congenitally hydronephrotic and normal Goettingen minipigs, using the whole-mount preparation technique. Whole-mount preparations of hydronephrotic (two with bilateral ectopic ureters, one with left distal ureteric stenosis) and normal (three) porcine upper urinary tracts were examined by immunohistochemistry with tyrosine hydroxylase (TH) and neurofilament and by histochemical staining with NADPH-diaphorase and acetylcholinesterase. Staining results were evaluated using normal bright-field and confocal laser scanning microscopy. Neurofilament-, TH-immunoreactive and acetylcholinesterase-positive nerve fibres and neuronal networks were identified in the adventitial, muscle and subepithelial layers of the whole upper urinary tract. An NADPH-diaphorase-positive network was expressed in the subepithelial layer and less densely in the muscle layer. The general distribution of the identified neuronal networks was similar in hydronephrotic and normal upper urinary tracts, but the density of these neuronal networks was less in the former. The most striking observation was the absence or marked reduction of neuronal networks in the stenotic part of the ureter in the pig with left distal ureteric stenosis. Whole-mount preparations provide a method for assessing the three-dimensional topography of neuronal networks in the different layers of the porcine upper urinary tract. Although the macroscopic differences between the hydronephrotic and normal porcine upper urinary tracts were striking, changes in the innervation pattern were less obvious, except in distal ureteric stenosis.

Catecholaminergic and acetylcholine esterase containing nerves of cranial and spinal dura mater in humans and rodents.

The innervation of cranial and spinal dura mater in humans and rodents was studied by examining several dural zones (vascular, perivascular, intervascular) in different regions. Characterization and distribution of dural acetylcholinesterase-positive nerve fibers, catecholaminergic nerve fibers, and mast cells are analyzed and discussed. The results of chemical and surgical sympathectomy as well as the relationships between catecholaminergic nerve fibers and mast cells are studied. Our results are discussed in the light of possible implications in the physiopathology of dural algic syndromes including cephalalgia and spinal pain.

Mast cell, myofibroblast and nerve terminal complexes in carbon tetrachloride-induced cirrhotic rat livers

Background/Aims: Extracellular matrices in liver fibrosis are known to be produced by myofibroblasts that are transformed from fat-storing cells. The development of the fibrotic process is thought to be mediated by various fibrogenic mediators. Recently, the involvement of mast cells and cholinergic neurotransmitters in fibrogenesis has been suggested. We have studied the distribution of these cells and cholinergic nerve fibers in normal rat livers and 6-week carbon tetrachloride-induced rat cirrhotic livers. Methods: Mast cells and myofibroblasts were identified by immunohistochemistry for mast cell tryptase (AA1) and α-smooth muscle actin. Cholinergic nerve fibers and terminals were localized using the acetyl-cholinesterase neurohistochemistry method for light and transmission electron microscopy. Results: In normal rat livers, a few nerve terminals were connected with fibroblasts near the vascular walls in the portal tracts. In contrast, in cirrhotic rat livers, numerous acetylcholinesterase-positive nerve fibers were observed in the fibrous septa, forming a network. Ultrastructurally, the nerve terminals were observed in close contact with mast cells and myofibroblasts in fibrous septa, forming characteristics mast cell/myofibroblast/nerve terminal complexes. In cirrhotic nodules, nerve terminals were situated in close contact with myofibroblasts in the periseptal sinusoids. These axon terminals contained numerous small clear vesicles, and acetylcholinesterase-positive products were noted in the space of the synaptic membranes. Conclusion: Our findings demonstrate that mast cell/myofibroblast/cholinergic nerve terminal complexes may play a role in the development of liver fibrosis, probably because of the production of extracellular matrix components by myofibroblasts.

The olfactory bulb in Alzheimer’s disease

This report describes the laminar distribution of acetylcholinesterase-positive structures in the human olfactory bulb of control and Alzheimer’s disease brain samples. Light microscopic histochemistry revealed the enzyme-positive neurons and nerve fibres. No acetylcholinesterase staining was present in the olfactory nerve layer, the glomerular layer or the external granule cell layer. A few enzyme-positive (cholinergic) nerve fibres were detected in the external plexiform layer and the white matter. A large number of cholinergic axons were present in the internal plexiform layer and the internal granule cell layer. Acetylcholinesterase-positive nerve fibres and cells were present in the mitral/tufted cell layer and the anterior olfactory nucleus. In Alzheimer’s disease brain samples, a weak and patchy acetylcholinesterase staining appeared in the internal plexiform layer and the internal granule cell layer. In the anterior olfactory nucleus, enzyme-positive neurofibrillary tangles and senile plaques were found. The neuropathological changes were studied with silver impregnation techniques and immunohistochemistry revealed a diffuse amyloid staining in the olfactory nerve layer and in the external plexiform layer, and large numbers of senile plaques in the glomerular layer and the anterior olfactory nucleus. The presence of amyloid positivity in the olfactory nerve layer and in a number of glomeruli suggests that no correlation exists between the cholinergic structures and the neuropathologic alterations in the human olfactory bulb in Alzheimer’s disease.

Preganglionic fibres of the adrenal medulla and cervical sympathetic ganglia: differential involvement during experimental American trypanosomiasis in rats.

The acute phase of experimental Chagas' disease in rats is associated with early lesions of the post-ganglionic sympathetic nerve terminals of the heart, the varicosities being the target. In the superior cervical and stellate ganglia the preganglionic fibres showed no signs of lesion in the course of experimental Chagas' disease. In the adrenal medulla, however, the acute phase of the Trypanosoma cruzi infection induced a clear rarefaction of the acetylcholinesterase-positive nerve fibres (20 and 32 days after infection). Recovery of the normal pattern occurred in most animals by day 125 after infection. At days 20, 32 and 46 after infection, electron-microscopic studies demonstrated the occurrence of damage in cholinergic nerve terminals contacting the chromaffin cells. The signs of damage included dense bodies, clumps of synaptic vesicles and filaments, rarefaction of all organelles, vacuoles and irregular contour. The ultrastructural peculiarities of the sympathetic ganglia may explain the ganglionar microenvironment protective against the hazardous factors elicited by acute Chagas' disease.

Morphological study of vagal innervation in human semilunar valves using a histochemical method.

To determine the innervation of human semilunar valves, we examined the pulmonary and aortic valves of the normal autopsied hearts of 3 men (53 to 71 years old). Whole valve tissues with the aorta or pulmonary trunk were stained for acetylcholinesterase by a histochemical method. Acetylcholinesterase-positive nerve fibers with a diameter of 2 to 20 mm were located on the ventricular side of the semilunar valves. Innervation of the semilunar valves was extremely sparse compared with that of the atrioventricular valves and that of the aortic or pulmonary arterial wall. The nerves originated from the subendocardium of the ventricles and the adventitia of the arterial walls. The nerves were more distributed in the basal site than in the marginal site of the semilunar valve. The nerve fibers formed a network in basal two-thirds of the leaflet. Thick nerves ramified in the thin nerve plexus. The thick nerves had a varicose-like structure. Thin nerves had a dot- and brush-like ending. The nerves in human semilunar valves may play a role in valve motion.

Scanning electron microscopic observations of nerves in the guinea-pig gallbladder after an acetylcholinesterase histochemistry.

Three-dimensional structures of the nerves of the guinea-pig gallbladder, after histochemical demonstration of the acetylcholinesterase activity and HCl hydrolysis-collagenase digestion, were examined by scanning electron microscope. HCl-collagenase digestion facilitated easy identification of silver- and gold-intensified acetylcholinesterase-positive nerve fibers at a high accelerating voltage (25 kV), due to their strong reflection image. Ganglia were either triangular or ovoidal in shape. Dense para- and peri-vascular nerve fibers occurred around the cystic artery. There were a few intramuscular nerve fibers with varicosity-like structures among smooth muscle bundles. Dense branched and tapering nerve fibers with varicosities in the lamina propria mucosae were closely attached to epithelial cells. The acetylcholinesterase-positive fibers in the lamina propria and peri- and para-vascular nerves, and fewer positive fibers in the smooth muscle layer probably represent cholinergic nerves involved in the concentration of biliary compounds and lesser in the motor function of the smooth muscle.

Electrogenic colonic ion transport in Hirschsprung's disease: reduced secretion to the neural secretagogues acetylcholine and iloprost.

The effects of the abnormal innervation in Hirschsprung's disease on colonic ion transport were examined in vitro using Ussing chambers. The response of the mucosal/submucosal preparations to different secretagogues were investigated in aganglionic and ganglionic rectosigmoid and transverse colon from children with Hirschsprung's disease and compared with normally innervated colon from children with anorectal anomalies. Basal values were similar in aganglionic and ganglionic rectosigmoid colon. Neurally mediated secretion with iloprost (10(-6) M) and acetylcholine (900 and 9 microM) was considerably reduced in aganglionic colon compared with normally innervated ganglionic colon. The ganglionic colon proximal to the aganglionic colon also had a reduced response to acetylcholine despite a normal acetylcholinesterase staining pattern. The responses to Escherichia coli STa enterotoxin (50 MU/ml) and isobutylmethylxanthine (10(-3) M) were similar in ganglionic and aganglionic colon. The response to STa enterotoxin was not changed by the nerve blocking agent tetrodotoxin (10(-6) M). The data show that colonocytes from aganglionic colon are capable of a normal secretory response if stimulated directly by cAMP or cGMP acting secretagogues but secretion in response to neurally mediated secretagogues is impaired. The hypertrophied acetylcholinesterase positive nerve fibres that infiltrate the aganglionic colon are likely to contribute to the reduced secretion to acetylcholine.

Noradrenergic and acetylcholinesterase-positive nerve fibres of the uterus in sexually immature and cycling rats.

The distribution and density of the noradrenergic and acetylcholinesterase-positive nerve fibres were histochemically studied in different uterine regions of prepubertal and cycling rats in dioestrus and oestrus. Besides the rich and double innervation of blood vessels, both types of nerve fibre were found in the myometrium and cervical musculature. The non-vascular noradrenergic network looked denser at the tubal end of the horns and at the cervix, whereas the acetylcholinesterase-positive innervation was poor at the tubal end, increasing toward the cervix. Contrasting with the middle third of the uterine horn, at the tubal end, the myometrial longitudinal layer was much more innervated than the circular one, especially by the noradrenergic nerve fibres. The prepubertal rats presented an adult pattern of uterine autonomic innervation. In the cycling animals, this innervation was nearly the same during oestrus and dioestrus regarding both the density of nerve fibres and intensity of the histochemical reactions.

Morphological study on vagal innervation in human atrioventricular valves using histochemical method.

To demonstrate innervation in human atrioventricular valves, we examined the tricuspid and mitral valves of apparently normal autopsied hearts of four men (ages ranging from 50 to 74 years). Whole valve tissues were stained for acetylcholinesterase by a histochemical method. Acetylcholinesterase-positive nerve fibers with a diameter of 2 to 5 microns were distributed widely in the deep atrialis of the atrioventricular valves and partly in the fibrosa. The nerve fibers formed a network or plexus from the base to the anatomical edge of the valves. Meshes of the nerve fiber network were more dense towards the base and at the commissure than either towards the edge or at the body. Thicker nerve fibers, which were interspersed coarsely in the leaflets, were intercalated by special varicose apparatuses at a few sites in their long running course. On the contrary, thinner nerve fibers which were distributed abundantly, ended, as a rule, in small dotor brush-like formations. Approximately half of the chordae tendineae were innervated by the nerve fibers. The mode of vagal innervation suggests that the nerve system may assist valve movement by moderating myocyte contraction in the valve base and change valve structure by sensing a stress in the valves.

The effects of epithelium removal on the actions of cholinomimetic drugs in opened segments and perfused tubular preparations of guinea‐pig trachea

1. Isolated segments of guinea-pig trachea or perfused tracheal tubes were arranged for the recording of trachealis tension changes in Krebs solution containing indomethacin (2.8 microM). 2. In opened tracheal segments, epithelium removal caused modest (2-3 fold) potentiation of the effects of acetylcholine (ACh) and methacholine (MeCh) but failed to potentiate carbachol (CCh), bethanechol (BeCh), oxotremorine or KCl. 3. Pretreatment with ecothiopate potentiated effects of ACh and MeCh but not of CCh or BeCh. Removal of epithelium in ecothiopate-treated tissue potentiated effects of ACh and MeCh but not of CCh or BeCh. 4. Guinea-pig ileum challenged with ACh was used as a bioassay system for cholinesterase activity. Scrapings of tracheal epithelium did not hydrolyse ACh. 5. Histochemical staining revealed no fibres positive for acetylcholinesterase or pseudocholinesterase in the tracheal epithelium. However, the underlying tissues contained acetylcholinesterase-positive nerve fibres and the trachealis muscle itself stained positively for pseudocholinesterase activity. 6. Neither tetrodotoxin (3 microM) nor hexamethonium (500 microM) modified the ability of epithelium removal to potentiate ACh. 7. In perfused tracheal tubes where spasmogens were added to the luminal perfusate, epithelium removal potentiated effects of ACh (31 fold), CCh (10 fold), oxotremorine (2 fold) and KCl. 8. In perfused tracheal tubes where spasmogens were added to the Krebs solution superfusing the adventitial surface of the tissue, epithelium removal significantly reduced the potency of CCh, oxotremorine and KCl. 9. It is concluded that the selectivity and magnitude of the potentiation of cholinomimetics caused by epithelium removal depends on the route by which the cholinomimetic agent gains access to the trachealis muscle. The potentiation of acetic acid esters of choline seen in opened tracheal segments does not reflect the loss of epithelial cholinesterase activity and does not depend on the activity of nervous reflex arcs in the tracheal wall. The reduced potency of adventitially-applied cholinomimetics and KCl seen in epithelium-denuded tissue strongly suggests that the epithelium can moderate trachealis sensitivity to cholinomimetic agents not only by releasing epithelium-derived relaxing factor but also by acting as a barrier to drug diffusion.

A Histochemical and Immunohistochemical Study of the Autonomic Innervation of the Lower Urinary Tract of the Female Pig. Is The Pig a Good Model for the Human Bladder and Urethra?

The detrusor muscle, bladder neck, proximal, middle and distal regions of the urethra of the female pig were studied by histochemical and immunohistochemical methods to localize catecholamine-containing, acetylcholinesterase-positive and peptide-containing nerves. The peptides examined included: vasoactive intestinal polypeptide, substance P, somatostatin, [Met] enkephalin, bombesin and gastrin. The greatest density of nerves was found in the smooth muscle of the distal urethra, followed by the bladder neck, middle urethra, and proximal urethra, with the least in the detrusor muscle. The greatest number of nerve fibres stained for acetylcholinesterase, followed by vasoactive intestinal polypeptide- and catecholamine-containing fibres. Substance P-immunoreactive nerve fibres were confined to the bladder neck and distal urethral regions. [Met] enkephalin- and gastrin-immunoreactive nerves were most dense in the distal urethra but absent in detrusor muscle, while somatostatin-immunoreactive nerve fibres were sparsely distributed throughout the lower urinary tract. No nerve fibres showing immunoreactivity to bombesin were found. Catecholamine-containing, acetylcholinesterase-positive, vasoactive intestinal polypeptide-, substance P-, [Met] enkephalin- and gastrin-immunoreactive nerves were also found on the adventitial-medial border of blood vessels in the pig urinary tract. In the intrinsic external urethral sphincter, located in the distal urethra, vasoactive intestinal polypeptide- and gastrin-immunoreactive nerve fibres were found bordering a small number of individual striated muscle fibres, while catecholamine-containing nerves were found predominantly in the connective tissue surrounding the striated muscle fibres. Dense populations of acetylcholinesterase-positive nerve fibres were found associated with the striated muscle fibres, with end plates on some of them. Intramural ganglia, composed of two to 30 neurones, were found in the bladder neck and middle and distal regions of the urethra. In the smooth muscle, and in the vicinity of the striated muscle regions of the intrinsic external urethral sphincter, there were small ganglia, containing two to three neurones, which were vasoactive intestinal polypeptide-, [Met]enkephalin- and somatostatin-immunoreactive. The results are compared to the autonomic innervation of the human bladder and urethra as previously described and it is concluded that the lower urinary tract of the pig is a good model for some features of the lower urinary tract of man, but a poor model for others.

Innervation of arteriovenous anastomoses in the brood patch of the domestic fowl.

The innervation of blood vessels in the brood patch (thoracic skin) of the domestic fowl was studied by use of the catecholamine fluorescence technique, acetylcholinesterase staining, and the immunoperoxidase technique for demonstration of vasoactive intestinal polypeptide (VIP). Large arteries and veins were sparsely innervated, whereas arteriovenous anastomoses (AVAs) were densely innervated by adrenergic, acetylcholinesterase-positive, and VIP-immunoreactive nerve fibres. The rich supply of different vasomotor nerves to AVAs emphasizes the importance of these vascular shunts in regulating blood flow and, in turn, the transport of heat to the brood patch. Furthermore, the presence of VIP-immunoreactive nerve fibres in the vasculature of the brood patch suggests that VIP might be the mediator of the previously reported cold-induced vasodilatation.