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.     

Connections between Adrenergic Nerves and other Tissue Components in the Eye

The connections between adrenergic nerve fibres and other ocular structures were studied in normal embryonic material (man, dogs, cats, guinea-pigs, and rats) as well as with a special vessel injection technique (adult rats, guinea-pigs, and rabbits). It was established that adrenergic fibres are a normal constituent of the cornea. The adrenergic nerves were more numerous in the embryo than in the adult, and also occurred within the embryonic corneal epithelium. These intraepithelial fibres disappear shortly after birth. Adrenergic fibres running in the connective tissue without connection to vessels were further found in the iris, the limbus region, the chamber angle (of the guinea-pig predominantly) and in the chorioid. It cannot be excluded that these fibres innervate some connective tissue component. In the sphincter pupillae, only a few adrenergic fibres were connected to the vessels, such as was the case also in the ciliary muscle of the guinea-pig. Under the ciliary epithelium of the ciliary body and the ciliary processes there was a thick and dense plexus of adrenergic fibres. Only a restricted number of them was associated with the vessels. The “capillaries” of the ciliary processes were remarkable in that they seemed to possess adrenergic fibres. No adrenergic innervation to the melanophores was apparent.     

Adrenergic and cholinergic innervation of the rag urinary bladder.

The autonimic innervation of the rat urinary bladder was studied using histochemical methods and nerve stimulations. A sparse adrenergic innervation of the detrusor muscle was found. It was supposed to originate from long adrenergic neurones. The trigonum area had a rich ssupply of adrenergic fibres, probably derived from short adrenergic neurones. A uniformly rich supply of acetylcholine-esterase (AChE)-positive nerves was found in the WHOLE BLADDER. Postganglionic sympathetic denervation caused no detectable change of adrenergic or AChE-positive nerves in the bladder, while parasympathetic decentralization or denervation produced a total disappearance of adrenergic fibres. The AChE-positive nerves were appreciably reduced in number after parasympathetic decentralization and not detectable after postganglionic denervation. Neither adrenergic nor AChE-positive ganglion cells could be demonstrated in the bladder wall. Electrical stimulation of the hypogastric nerves or the pelvic nerves distal to the pelvic ganglia elictied contraction of the detrusor muscle. The responses were not affected by hexamethonium, dihydroergotamine or proparanolol but were slightly reduced by guanethidine, reduced to about 40% by atropine and potentiated by eserine. Stimulation of the pelvic nerve proximal to the pelvic ganglion was partially blocked by hexamethonium. It si concluded that the urinary bladder of the rat is supplied by postganglionic adrenergic fibres mainly via the pelvic nerves and only to a lesser extent via the hypogastric nerves. Probably cholinergic fibres pass to the bladder mainly via the pelvic nerves but also via the hypogastric nerves, having their cellbodies outside the bladder wall, partly proximal to the pelvic ganglia.     

Adrenergic and Cholinergic Nerves of the Human Urethra and Urinary Bladder. A Histochemical Study

The occurrence and distribution of adrenergic and acetylcholine esterase (AChE) positive nerves in the human urethra and urinary bladder were studied histochemically with the fluorescence method of Falck and Hillarp, and the copper thiocholine method of Koelle and Friedenwald. Both types of nerves were mainly confined to the layers of smooth muscle cells in the walls of the organs. In all parts of the urethra, there was a scanty supply of adrenergic nerves. Few adrenergic nerves were also found in the urinary bladder, except in the trigone area, where they were abundant. AChE-positive nerves were uniformly and richly distributed in the urinary bladder. Throughout the urethra the distribution of AChE-positive nerve fibres was uniform, but the number was clearly less than in the urinary bladder. No intramurally located adrenergic or AChE-positive ganglion cells could be demonstrated.     

Adrenergic and Cholinergic Innervation of the Rat Urinary Bladder

The autonomic innervation of the rat urinary bladder was studied using histochemical methods and nerve stimulations. A sparse adrenergic innervation of the detrusor muscle was found. It was supposed to originate from long adrenergic neurones. The trigonum area had a rich supply of adrenergic fibres, probably derived from short adrenergic neurones. A uniformly rich supply of acetylcholine-esterase (AChE)-positive nerves was found in the whole bladder. Postganglionic sympathetic denervation caused no detectable change of adrenergic or AChE-positive nerves in the bladder, while parasympathetic decentralization or denervation produced a total disappearance of adrenergic fibres. The AChE-positive nerves were appreciably reduced in number after parasympathetic decentralization and not detectable after postganglionic denervation. Neither adrenergic nor AChE-positive ganglion cells could be demonstrated in the bladder wall. Electrical stimulation of the hypogastric nerves or the pelvic nerves distal to the pelvic ganglia elicited contraction of the detrusor muscle. The responses were not affected by hexamethonium, dihydroergotamine or propranolol but were slightly reduced by guanethidine, reduced to about 40% by atropine and potentiated by eserine. Stimulation of the pelvic nerve proximal to the pelvic ganglion was partially blocked by hexamethonium. It is concluded that the urinary bladder of the rat is supplied by postganglionic adrenergic fibres mainly via the pelvic nerves and only to a lesser extent via the hypogastric nerves. Probably cholinergic fibres pass to the bladder mainly via the pelvic nerves but also via the hypogastric nerves, having their cellbodies outside the bladder wall, partly proximal to the pelvic ganglia.     

The districution of biogenic amines in the carotid bifurcation region

1. The distribution of phenolic amines in the carotid body and of adrenergic nerves in the arterial walls of the carotid bifurcation region was investigated histochemically using the phenolic amine-formaldehyde gas condensation reaction, with supplementary electron microscopical examination. Studies were conducted on normal rabbits and on rabbits after superior cervical ganglionectomy.2. The glomus cells of the carotid body contain phenolic amines. The cellular amine persists after long-term sympathetic ganglionectomy.3. The blood vessels supplying the carotid body receive an adrenergic innervation which disappears following superior cervical ganglionectomy.4. The walls of the carotid sinus contain adrenergic nerve fibres derived from the superior cervical ganglion.5. There is no penetration of the arterial tunica media by vasomotor fibres in any part of the carotid bifurcation region.6. Ultimate terminations of adrenergic nerves upon smooth muscle occur across the medio-adventitial border of the common, internal and external carotid arterial walls but only in relation to smooth-muscle cells in the adventitia of the carotid sinus wall.     

Micromorphology and histochemistry of polysaccharides in the goat mandibular salivary gland

The micromorphology and histochemistry of mucosubstances in mandibular salivary gland of goat were studied. Encapsulated ganglia were present in the interlobular connective tissue giving nerve fibres to the ducts and blood vessels therein. The mandibular gland of goat was a mixed tubuloacinar gland possessing mucous tubules and acini, the latter capped by seromucous demilunes. The mucous secretory units contained high amounts of neutral and acidic sulfated mucosubstances. The seromucoid demilunes contained neutral and less acidic nonsulfated mucosubstances. No glycogen was found in both types of secretory cells.     

Re-establishment of neurochemical coding of preganglionic neurons innervating transplanted targets

We investigated the effect on neurochemical phenotype of changing the targets innervated by sympathetic preganglionic neurons. In neonatal rats, the adrenal gland was transplanted into the neck, to replace the postganglionic neurons of the superior cervical ganglion. Transplanted adrenal glands survived, and contained noradrenergic and adrenergic chromaffin cells, and adrenal ganglion cells. Retrograde tracing from the transplants showed that they were innervated by preganglionic neurons that would normally have supplied postganglionic neurons of the superior cervical ganglion. The neurochemical phenotypes of preganglionic axons innervating transplanted chromaffin cells were compared with those innervating the normal adrenal medulla or superior cervical ganglion neurons. As in the normal adrenal gland, preganglionic nerve fibres apposing transplanted chromaffin cells were cholinergic. The peptide and calcium-binding protein content of preganglionic fibres was similar in normal and transplanted adrenal glands. In both cases, cholinergic fibres immunoreactive for enkephalin targeted adrenergic chromaffin cells, whilst cholinergic fibres with co-localised calretinin-immunoreactivity innervated noradrenergic chromaffin cells and adrenal ganglion cells. In contrast to the innervation of normal adrenal glands, these axons lacked immunoreactivity to nitric oxide synthase. In a set of control experiments, the superior cervical ganglion was subjected to preganglionic denervation in rat pups the same age as those that received adrenal transplants, and the ganglion was allowed to be re-innervated over the same time course as the adrenal transplants were studied. When the superior cervical ganglion was re-innervated by preganglionic nerve fibres, we observed that all aspects of chemical coding were restored, including cholinergic markers, nitric oxide synthase, enkephalin, calcitonin gene-related peptide and calcium binding proteins in predicted combinations, although the density of nerve fibres was always lower in re-innervated ganglia. These data show that the neurochemical phenotypes expressed by preganglionic neurons re-innervating adrenal chromaffin cells are selective and similar to those seen in the normal adrenal gland. Two explanations are advanced: either that contact of preganglionic axons with novel target cells has induced a switch in their neurochemical phenotypes, or that there has been target-selective reinnervation by pre-existing fibres of appropriate phenotype. Regardless of which of these alternatives is correct, the restoration of normal preganglionic codes to the superior cervical ganglion following denervation supports the idea that the target tissue influences the neurochemistry of innervating preganglionic neurons.     

Re-evaluation and quantification of the different sources of nerve fibres supplying the rat eye

The denervation and/or the removal of peripheral nerve ganglia are useful surgical techniques for studying the source and distribution of peripheral nerves in all organs, including the eye. The amount and distribution of the remaining nerve fibres supplying the eye (after sectioning of various types of nervous fibres and/or removal of nerve ganglia) were evaluated in the rat. Male Sprague-Dawley rats were anaesthetized and one or more of the following nervous tissues were removed: superior cervical ganglion, main ciliary ganglion, pterygopalatine ganglion, trigeminal ganglion and the ophthalmic-maxillary nerve. In some animals, chemical sympathectomy was performed by administration of 6-OH dopamine. The eyes were cut in serial sections, but only three regions (cornea, iris and choroid) were harvested and submitted for various nerve fibre staining techniques. The results were quantified and statistically analysed. Superior cervical ganglionectomy and/or chemical sympathectomy induced the destruction of almost all the catecholaminergic nerve fibres in the three examined regions of the rat eye. Removal of the ciliary ganglion (partial parasympathectomy) caused the destruction of about 60% of the cholinergic nerve fibres of the same regions of the rat eye, while subtotal parasympathectomy destroyed about 80% of the cholinergic nerve fibres. Surgical transsection of the ophthalmo-maxillary nerve or the removal of the trigeminal ganglion led to a degeneration of almost all sensitive nerve fibres of the three examined regions of the rat eye. The denervation experiments confirmed the presence of the different types of nerve fibres (sympathetic, parasympathetic and sensitive) in the three studied structures of the rat eye.     

Peptide containing nerves in the ureter of the guinea-pig and cat

We report the presence of two regulatory peptides, substance P and vasoactive intestinal polypeptide (VIP), in the ureter and their localisation by both light- and electron-microscopy to autonomic nerves. VIP- and substance P-like immunoreactive nerves showed, in general, a similar anatomical distribution in the various layers of the ureter. Immunoreactive nerves were observed running along the smooth muscle coat, parallel to muscle bundles, around blood vessels and in the submucosa, particularly beneath the epithelium. In addition, scattered VIP-like immunoreactive ganglion cells and nerve fibres were seen in adventitial ganglia around the most distal part of the ureter and ureter-bladder junction in the cat. The guinea-pig ureter contained principally substance P-like immunoreactivity, whereas the cat ureter possessed mainly VIP-like material.The distribution of adrenergic and cholinergic nerves was compared with those containing peptides. Peptide-containing nerves had a more extensive distribution than adrenergic ones, which were mainly associated with blood vessels; however, cholinergic nerves were often localised in the same areas as those possessing peptides. Conventional electron microscopy revealed that separate p-type (peptidergic) and cholinergic nerve terminals were frequently present in the same nerve bundles, although in the cat ureter some 50% of the p-type profiles contained a mixed population of vesicles, characteristic of both cholinergic and p-type nerves. VIP- and substance P-like immunoreactivity were also localised at the ultrastructural level by means of a gold-labelled goat-antirabbit serum.     

Tumours may be innervated

It is generally assumed that tumours are not innervated. However, following an accidental observation of a nerve fibre within an adenoma of the ciliary body epithelium of the eye, we have further examined two such tumours. One pigmented and one non-pigmented adenoma of the ciliary body epithelium (APCE and ANCE, respectively) that had been surgically removed from two human eyes were processed for ultrastructural evaluation and systematically screened and analysed for the occurrence of nerve tissue under a transmission electron microscope. The adenomas were composed of epithelial tumour cell strands and interposed vascularised connective tissue. Both tumours contained a small number of fine unmyelinated nerve fibres containing clear and dense core vesicles. In both adenomas, the nerve fibres were located in the tumour periphery close to blood vessels and tumour cells. In the APCE, they were also seen in more central areas. Since nerves always have a function, this finding, if confirmed in other neoplasms, may influence our understanding of such innervated tumours.     

The adrenergic and AChE-positive nerves in pig vagina

The experiments were performed on 5 sexually immature and 6 mature pigs. The segments of vagina were collected and then cut by means of a freezing microtome. The adrenergic nerves were detected according to Torre and Surgeon's (1976) glyoxylic method, and examined under a fluorescent microscope. Presence of AChE-positive fibers was detected using Karnovsky-Roots (1964) method. Both the adrenergic and the AChE-positive fibres were found in all layers of vaginal and around the blood vessels. As results from the studies, pig vagina is much more innervated with AChE-positive nerves than with adrenergic ones. Distribution pattern of these fibers is similar in all layers of the vagina. No differences were found between innervation of vagina in sexually mature and immature pigs.     

Fine structure of the rat carotid body transplanted into the anterior chamber of the eye

Summary Rat carotid bodies transplanted into the anterior chamber of the eye were studied by electron microscopy. Chief and sustentacular cells and a few ganglion cells survived for 3 months and maintained cytological characteristics similar to those in the intact carotid body. The transplant contained many fenestrated capillaries. Chief cells at the periphery of the cell cluster had long cytoplasmic processes which projected into the stroma of the iris. The cell processes became incorporated into bundles containing nerve fibres, which were enveloped by a perineurial sheath. Three types of nerve fibres were identified in the explant. Type I and type II nerve fibres (presumptive cholinergic and adrenergic, respectively) were enclosed by sustentacular and satellite cells. Most of the nerve fibres were completely separated from chief cells and ganglion cells by sustentacular and satellite cells. A few nerve fibres made direct apposition to chief cells and ganglion cells, where some nerves were presynaptic to them. Type III nerve fibres derived from myelinated nerve fibres were also enclosed by sustentacular and satellite cells.     

The fine structure of the monkey submandibular gland with a special reference to intra-acinar nerve endings

The secretory terminations of monkey submandibular gland were studied by electron microscopy. The acini are composed of two types of secretory cells which are presumably serous and mucous in type. Myoepithelial cells are present also in the acini. The peri-acinar connective tissue contains many unmyelinated nerve fibers. In some portions, the axons contain many synaptic vesicles of various types. These nerve endings partially lose their Schwann cell investment and reach the acinar basement membrane. In peri-acinar connective tissue two types of nerve endings may be recognized. They are thought to be adrenergic and cholinergic in type. On the other hand, only one type of nerve ending (cholinergic) is observed within the acini. The intra-acinar nerve endings are not surrounded by Schwann cell cytoplasm and make direct contact with plasma membranes of the myoepithelial and mucous cells, with a space about 200 Å wide intervening between the nerve and terminal cell. No nerve endings occur in the interspaces between the serous cells. Also, the ultrastructure of the secretory and myoepithelial cells is described.     

Neuropeptide Y co-exists with vasoactive intestinal polypeptide and acetylcholine in parasympathetic cerebrovascular nerves originating in the sphenopalatine, otic, and internal carotid ganglia of the rat

Neuropeptide Y co-exists with noradrenaline in the majority of the sympathetic nerves supplying cerebral blood vessels. However, after sympathectomy in the rat the number of cerebrovascular neuropeptide Y nerve fibers are only reduced in number despite a complete disappearance of the adrenergic markers. The origin of these non-sympathetic neuropeptide Y fibers was studied by nerve transections and retrograde axonal tracing utilizing True Blue. Three days after bilateral superior cervical sympathectomy, the number of neuropeptide Y-containing nerve fibers decreased to about 40% of that in non-treated animals. One week after True Blue application on the proximal portion of the middle cerebral artery, the tracer accumulated in neurons of the sphenopalatine, otic, and internal carotid ganglia. Of these cells 80%, 95% and 5%, respectively, were neuropeptide Y-positive. Some of the True Blue/neuropeptide Y-positive cells displayed immunoreactivity for vasoactive intestinal polypeptide and some were positive for choline acetyltransferase. Two weeks after bilateral removal of the sphenopalatine ganglion or transection of postganglionic fibers from the ganglion reaching the pial vessels through the ethmoidal foramen, together with subsequent sympathectomy, no neuropeptide Y-containing nerve fibers could be observed on the anterior cerebral and internal ethmoidal artery or the distal portion of the middle cerebral artery, whereas a few nerve fibers remained on the proximal portion of the middle cerebral artery, internal carotid artery, and the rostral portion of the basilar artery. In conclusion, neuropeptide Y in cerebrovascular nerves is co-stored not only with noradrenaline in sympathetic nerves from the superior cervical ganglion, but also with acetylcholine (reflected in the presence of choline acetyltransferase) and vasoactive intestinal polypeptide in parasympathetic nerves originating in the sphenopalatine, otic, and internal carotid ganglia.     

Innervation of the C cells of chicken ultimobranchial glands studied by immunohistochemistry,fluorescence microscopy,and electron microscopy

Innervation of the ultimobranchial glands in the chicken was investigated by immunohistochemistry, fluorescence microscopy and electron microscopy. The nerve fibers distributed in ultimobranchial glands were clearly visualized by immunoperoxidase staining with antiserum to neurofilament triplet proteins (200K-, 150K- and 68K-dalton) extracted from chicken peripheral nerves. The ultimobranchial glands received numerous nerve fibers originating from both the recurrent laryngeal nerves and direct vagal branches. The left and right sides of the ultimobranchial region were asymmetrical. The left ultimobranchial gland had intimate contact with the vagus nerve trunk, especially with the distal vagal ganglion, but was somewhat separated from the recurrent nerve. The right gland touched the recurrent nerve, the medial edge being frequently penetrated by the nerve, but the gland was separated from the vagal trunk. The left gland was innervated mainly by the branches from the distal vagal ganglion, whereas the right gland received mostly the branches from the recurrent nerve. The carotid body was located cranially near to the ultimobranchial gland. Large nerve bundles in the ultimobranchial gland ran toward and entered into the carotid body. By fluorescence microscopy, nerve fibers in ultimobranchial glands were observed associated with blood vessels. Only a few fluorescent nerve fibers were present in close proximity to C cell groups; the C cells of ultimobranchial glands may receive very few adrenergic sympathetic fibers. By electron microscopy, numerous axons ensheathed with Schwann cell cytoplasm were in close contact with the surfaces of C cells. In addition, naked axons regarded as axon terminals or “en passant” synapses came into direct contact with C cells. The morphology of these axon terminals and synaptic endings suggest that ultimobranchial C cells of chickens are supplied mainly with cholinergic efferent type fibers. In the region where large nerve bundles and complex ramifications of nerve fibers were present, Schwann cell perikarya investing the axons were closely juxtaposed with C cells; long cytoplasmic processes of Schwann cells encompassed large portions of the cell surface. All of these features suggest that C-cell activity, i.e., secretion of hormones and catecholamines, may be regulated by nerve stimu1i.     

Coexistence and plasticity of neurotransmitters and neuropeptides in the rat iris.

The presence, distribution and origin of substance P (SP), neuropeptide Y (NPY), and CGRP-immunoreactive axons in rat iris were investigated in whole mount preparations, with special respect to the localization of the "classical" adrenergic and cholinergic ground plexuses. SP-IR fibres are distributed parallel to the pupillary margin in the sphincter muscle, and in an irregular plexus in the dilator muscle. The distribution of CGRP-IR fibres was similar to this. Both SP- and CGRP-IR elements originated from the Gasserian ganglion. Following electrocoagulation of the ophthalmic nerve, both SP- and CGRP-IR nerves completely disappeared, while in the caudal nucleus of the trigeminal nerve a substantial decrease of the immunoreactivity was found. NPY-IR fibres have also been demonstrated in the anterior uvea, displaying a pattern similar to that of the adrenergic nerves. In the sympathectomized iris, there was a marked decreased in the density of NPY-IR fibres indicating that NPY most likely coexists with the classical sympathetic neurotransmitter, noradrenalin in the sympathetic nerve supply deriving from the superior cervical ganglion. 1 month after sympathectomy, there was an increase in the density (and possibly also in the number) of both SP- and CGRP-IR fibres in the denervated iris. Subsequent immuno-electron microscopic analysis has demonstrated that both SP- and CGRP-IR fibres are unmyelinated axons, embedded in a common Schwann cell cytoplasm together with a number of axons devoid of immunoreactivity.(ABSTRACT TRUNCATED AT 250 WORDS)     

The origin of extrinsic nitrergic axons supplying the human eye

Nitrergic nerve fibres of intrinsic and extrinsic origin constitute an important component of the autonomic innervation in the human eye. The intrinsic source of nitrergic nerves are the ganglion cells in choroid and ciliary muscle. In order to obtain more information on the origin of extrinsic nitrergic nerves in the human eye, we obtained superior cervical, ciliary, pterygopalatine and trigeminal ganglia from six human donors, and stained them for neuronal nitric oxide synthase (nNOS) and nicotinamide adenine dinucleotide phosphate-diaphorase (NADPH-D). In the superior cervical ganglia, nNOS/NADPH-D-positive varicose axons were observed whereas perikarya were consistently negative. Fewer than 1% of perikarya in the ciliary ganglia were labelled for nNOS/NADPH-D. The diameter of nNOS/NADPH-D-positive ciliary perikarya was between 8 and 10 microm, which was markedly smaller than the diameter of the vast majority of negative perikarya in the ciliary ganglion. More than 70% of perikarya in the pterygopalatine ganglia were intensely labelled for both nNOS and NADPH-D. In trigeminal ganglia, 18% of perikarya were nNOS/NADPH-D-positive. The average diameter of trigeminal nNOS/NADPH-D perikarya was between 25 and 45 microm. Pterygopalatine and trigeminal ganglia are the most likely sources for extrinsic nerve fibres to the human eye.     

新生儿胆总管末端与十二指肠连接处的神经支配

本文采用诱发荧光和胆碱酯酶组化、髓鞘染色、镀银等技术,对41例新生儿胆总管末端与十二指肠连接处的神经分布进行了系统地观察。证明该区有丰富的胆碱能、肾上腺素能神经分布,神经的密度与平滑肌的含量有关。在此区内未见肾上腺素能节后神经元,但可见副交感节后神经元,后者属DogielⅠ型和DogielⅡ型神经细胞。大小不等的AChE阳性神经节,神节丛节位于外膜、肌层及乏特氏壶腹粘膜下。在该区外膜处的血管附近还发现ButhE阳性小神经节、小神经节群。ButhE阳性神经纤维布于粘膜下及血管壁,并在血管附近形成小丛。     

Neuronal pathways to the rat thyroid revealed by retrograde tracing and immunocytochemistry

The distribution and origin of the nerve fibres innervating the rat thyroid were studied by immunocytochemistry, retrograde tracing and denervation experiments. Immunocytochemistry revealed nerve fibres containing noradrenaline, neuropeptide Y, vasoactive intestinal peptide, peptide histidine-isoleucine, galanin, substance P, neurokinin A and calcitonin gene-related peptide around blood vessels and follicles. Many of these transmitter candidates were found to co-exist with each other in different combinations in different subpopulations of neurons. Sympathectomy eliminated all noradrenaline- and noradrenaline/neuropeptide Y-containing fibres in the thyroid. Cervical vagotomy eliminated about 50% of the galanin-, substance P- and calcitonin gene-related peptide-containing fibres. Local denervation (removal of the thyroid ganglion and the thyroid nerve) eliminated all galanin- and substance P-immunoreactive fibres and the majority of noradrenaline-, noradrenaline/neuropeptide Y-, vasoactive intestinal peptide- and calcitonin gene-related peptide-containing fibres in the thyroid gland. Injection of True Blue into the thyroid gland labelled cell bodies in the thyroid ganglion, the laryngeal ganglion, the superior cervical ganglion, the jugular-nodose ganglionic complex, the dorsal root ganglia (C2-C5) and the trigeminal ganglion. Judging from the number of labelled nerve cell bodies, the superior cervical ganglion and the thyroid ganglion contribute most to the thyroid innervation, while the laryngeal ganglion and the trigeminal ganglion contribute least. The True Blue-labelled ganglia were examined for the presence of various populations of nerve cell bodies (only major populations are listed). The thyroid ganglion harboured neuropeptide Y, vasoactive intestinal peptide and galanin/vasoactive intestinal peptide cell bodies (in order of predominance); the laryngeal ganglion galanin/vasoactive intestinal peptide, vasoactive intestinal peptide and calcitonin gene-related peptide cell bodies; the superior cervical ganglion noradrenaline/neuropeptide Y and noradrenaline cell bodies; the jugular ganglion calcitonin gene-related peptide, substance P/calcitonin gene-related peptide and galanin/substance P/calcitonin gene-related peptide cell bodies; the nodose ganglion vasoactive intestinal peptide and vasoactive intestinal peptide/galanin cell bodies; the dorsal root ganglia (C2-C5) and the trigeminal ganglion calcitonin gene-related peptide, substance P/calcitonin gene-related peptide and galanin/substance P/calcitonin gene-related peptide cell bodies.(ABSTRACT TRUNCATED AT 400 WORDS)