The functions of bile ducts in sheep

Pressure changes in the gallbladder and the bile flow and pressure changes in the common bile duct were determined in sheep. The experiments were conducted on animals with external junction of choleslochus and cholecystostomy performed previously. The experiments demonstrated pressure in the sheep of the functional sphincter of Mirizzi at the boundary between the intrahepatic and extrahepatic bile ducts. A correlation was demonstrated also between the function of this sphincter and that of Oddi's sphincter. The conditions for bile filling of the extrahepatic bile ducts and gallbladder were determined. The process of bile excretion into the duodenum and the role of bile duct sphincters in this process are discussed. Attention is called to the relationship between the pressure in the gallbladder and the tonus of bile duct sphinters.     

Adrenergic innervation of the myocardium and skeletal musculature of the rabbit exposed to vibration

Innervation of the myocardium and that of foreleg musculature has been studied in rabbits subjected to the local vibration effect. The point where the vibration is applied is the foreleg, because its nerve plexuses are in the tightest way connected with the cardiac nervous apparatus. For treatment of the sections incubation in 2% solution of glyoxylic acid is used, which is followed with luminescent microscopy. While studying adrenergic nerve plexuses of the right auricle, their luminescent activity is stated to decrease more than by a half. In the ventricles only single perivascular adrenergic nerve plexuses remain. A constant reaction of the plexuses mentioned is revealed not only in the right, but in the left extremity subjected to a direct vibration. Taking into account that the vibrational effect is performed as a generalized action and it embraces the whole skeleton of the animal, it is possible to suggest that the activity of the sympathetic nervous plexuses results in a constant influence of noradrenaline on the wall of blood vessels producing their steady spasmodicity.     

New findings on the innervation of nerves proper]

The study by the author and his co-workers of the innervation of the sheaths of extraorganic (spinal and cerebral) and intraorganic nerves has shown that their nervous apparatus is differentiated in accordance with differentiation of epi-, peri- and endoneurium. The peculiar features of the innervation of sheaths of different nerves correspond to their functions and pathoplastical individuality and manifest themselves by uneven complexity, concentration and microtopography of nerve structures in the sheaths and by distinctions in the development and reactivity. Interrelationships and correlation was established between the specific functional readiness of nerve conductors and the structural organization of their sheaths' nervous apparatus. The phenomenon of reciprocal innervation of nerves was established in experiment as well as earlier reactive and compensatory-reparative processes in the nervous apparatus of nerve sheaths as compared with their conductors.     

Changes in the innervational connections of the urinary bladder upon experimental stimulation of the hypothalamus]

The innervation of the urinary bladder was studied in 40 rabbits, 5 of which were control and in 35 animals the posterior and anterior nuclei of the hypothalamus were stimulated by electric current through bipolar electrodes. The efferent innervation connections in whose terminal plexuses there occurred absorption of catecholamines were shown histochemically and neurohistologically to be involved in the pathological process. Reactive and degenerative changes were found to take place in receptory nerve terminations, and first of all in free ones. Then the bodies of pseudounipolar neurons of spinal ganglia were changed. Changes were also found in the connections of sensory neurons with the cells of Goll's and Burdach's nuclei.     

Sensory nerve endings of highly mobile structures in two marine teleost fishes

Summary With the use of a whole mount silver impregnation technique, sensory nerve endings were located in the connective tissue at the base of the modified pectoral fin ray in the gurnard,Aspitrigla cuculus, and within the perichondrium of the barbel in the goatfish,Mullus surmuletus. The location of these endings and their planar receptory fields in such highly mobile structures, suggests that the sensory endings are proprioceptive in nature and that they are associated in monitoring the positional state of the modified pectoral fin ray and barbel, respectively, during voluntary movement. This investigation addresses itself to the general problem of proprioception in teleost fishes and provides histological evidence for the presence of proprioceptive nerve endings.     

The nervous system in planarians: Peripheral and gastrodermal plexuses,pharynx innervation,and the relationship between central nervous system structure and the acoelomate organization

The Champy-Maillet osmium tetroxide-zinc iodide technique and a new method using azur B-sodium thioglycolate were used to study the general nervous tissue structure in planarians. A subepidermal and a submuscular nerve plexus, partially reported by earlier authors, are described, and a gastrodermal plexus is reported for the first time in triclads. The possible functions for each one of these plexuses are discussed. By the Champy-Maillet method, the innervation within the parenchyma appears as an array of numerous single nerve fibers that course between the parenchyma cells making apparent synaptic contacts. The pharynx has outer and inner nerve nets similar in structure to the submuscular nerve plexus. Both nerve nets are connected to each other by radial nerves. The central nervous system has a sponge-like structure with many lacunae filled with cell bodies, dorso-ventral muscle fibers, parenchymal cell processes and excretory ducts. The existence of this sponge-like nervous tissue structure is discussed in relation to the still incomplete centralization of the nervous tissue in these organisms, to the lack of a true vascular system and to the acoelomate level of organization. A comparison with the nervous tissue structure of more advanced groups like polyclads and nemertines is suggested.     

Immunohistochemical study on the distribution of vasoactive intestinal polypeptide (VIP) containing nerve fibers in the chicken pancreas

The distribution of vasoactive intestinal polypeptide (VIP) containing nervous elements in the chicken pancreas was immunohistochemically investigated by light microscopy. Strongly VIP immunoreactive ganglia existed in the interlobular connective tissue. Ganglion containing both VIP immunoreactive and non-immunoreactive nerve cells was occasionally observed in the connective tissue. Almost all the ganglion cells also showed acetylcholinesterase (AChE) activity. No extrapancreatic nerve bundles containing VIP immunoreactive nerve fibres were detected. VIP immunoreactive nerve fibres formed plexuses in the subepithelial layer of secretory ducts and the muscle layer of small arteries. The distribution pattern of VIP immunoreactive nerve fibers was similar to that of AChE-positive nerve fibers on adjacent sections. The exocrine pancreas received a rich supply of varicose nerve fibers showing VIP immunoreactivity. B-islets also were richly innervated by VIP immunoreactive varicose nerve fibers, whereas A-islets, only poorly. These observations suggest that VIP containing nerves in the chicken pancreas have an intrinsic origin, are probably derived from VIP immunoreactive, intrapancreatic ganglion cells and innervate secretory ducts, arteries, acinar cells and B-islets, and that VIP must coexist with acetylcholine in the nervous elements.     

Adrenergic and cholinergic innervation of the prostate in laboratory animals

The prostate innervation has been studied in 50 white rats, 12 rabbits, 12 guinea pigs, 6 cats and 6 dogs. Together with the impregnation techniques, Karnovsky-Roots method has been applied, for revealing cholinergic components, and the incubation method in 2% solution of glyoxylic acid, for revealing adrenergic nervous structures. Density of adrenergic and cholinergic nervous plexuses has been estimated by means of the planimetric point method. The prostate of the laboratory animals possesses well manifested adrenergic and cholinergic nervous plexuses. The organ's alveolus and ducts are covered with adrenergic and cholinergic fibers, however, the relative density of the cholinergic plexuses is less than that of the adrenergic ones. The guinea pig prostate is the most richly supplied with the adrenergic nervous plexuses, and the rabbit prostate--with the cholinergic nervous plexuses.     

Distribution of neuropeptide Y and vasoactive intestinal polypeptide immunoreactive nerves in normal and transplanted pancreatic tissue

Neuropeptide Y (NPY) and vasoactive intestinal polypeptide (VIP) immunoreactive nerves were demonstrated in 21-day-old embryonic pancreatic tissue fragments transplanted into the anterior eye chamber of rats for 22, 45 and 109 days and in 60-day-old normal adult pancreas using immunohistochemical technique. In normal adult tissue, NPY-positive neurons lie close to the basal and lateral walls of the acinar cells. NPY-containing nerve fiber plexuses were found around blood vessels. VIP-immunopositive nerves were also discernible in the outer parts of the islets of Langerhans and on pancreatic ducts. In the transplants, it is not only the neural elements that survived but also the pancreatic ducts and the endocrine cells. VIP- and NPY-positive neurons were found in the stroma of the surviving pancreatic tissue. The distribution of these neural elements is similar to that of normal tissue in the surviving pancreatic ducts but different with regards to the acinar tissue. This study confirms that intrinsic nerves can survive and synthesize polypeptides even after 109 days of transplantation into the anterior eye chamber.     

Correlative ontogenetic development of catecholamine- and LHRH-containing nerve endings in the median eminence of the rat

Summary The ontogenetic development of catecholamine (CA)-and LHRH-containing nerve endings in the median eminence of the rat was investigated by combining fluorescence histochemistry and immunohistochemistry in the same tissue section. LHRH-terminals appeared earlier than CA-terminals and were already detectable in the lateral part of the external layer of the central ME on the first day after birth. CA-nerve endings were first seen in a corresponding region of the ME on the seventh postnatal day. At this stage both types of terminals showed the earliest manifestation of a correlative pattern of their distribution. Subsequently the development of both types of nerve endings proceeded rapidly, and at 14 days their distribution pattern corresponded to that in adult animals. The authors conclude that at this stage the CA-neurons play a constant and significant role in the release of LHRH into the portal capillaries. The correlation between both types of nerve endings and the ontogenetic development of the capillary plexuses of the hypophysial portal system is discussed.This work was supported in part by a grant (No. 248093, 321426) from the Ministry of Education, Science and Culture, Japan     

Development of the neural apparatus of the human pancreas in prenatal ontogeny

In human embryos, prefetuses and fetuses from 6 to 40 weeks of development 82 preparations of the pancreas have been studied; 39 series of slices of the human embryos have been impregnated after Bielschowsky-Boeke. For the first time the nerves grow into the pancreas anlage in embryos of 16 mm long (6 weeks). The main sources supplying the pancreas with the nerves in the period studied are nervus vagus, celiac, hepatic, splenic, right adrenal, superior mesenteric and intermesenteric plexuses. Three stages in formation of the innervational apparatus of the pancreas are distinguished during the intrauterine development. The first stage is characterized by beginning of the nerve growing into the pancreas anlage. For the second stage an increased development of the intraorganic innervational apparatus and appearance of the all main sources of the organ's innervation are specific. The third stage is characterized with an increased differentiation of receptor zones in various parts of the pancreas. The development of the pancreatic innervational apparatus by the time of birth is not completed.     

Nerve endings in the heart of teleosts

The nerve endings in the heart of fishes were studied using silver impregnation techniques. The heart chambers are profusely innervated by the sympathetic, parasympathetic (vagal) and postganglionic fibers of the intracardiac ganglia situated at the sinuatrial and the atrioventricular junctions. The plexuses are composed of medullated and nonmedullated fibers. The nerve fibers generally end freely and are slightly branched or unbranched terminations of myelinated and unmyelinated fibers. Moreover, a few nerve fibers end redundant in the form of end-rings, bulb-like, bush-like, club-shaped end end-coil like structures. The complex unencapsulated types of endings are also found in the myocardium of the atrium and the ventricle. The encapsulated endings (Vater-Pacinian; Krause end-bulb) could not be observed.     

Cholinergic innervation of the pancreas in the sheep

Antibodies raised against vesicular acetylcholine transporter (VAChT) were applied to study the cholinergic innervation pattern of the pancreas of the sheep. To determine whether the cholinergic pancreatic neuronal elements contain tyrosine hydroxylase (TH), neuropeptide Y (NPY), vasoactive intestinal peptide (VIP) or substance P (SP) double immunocytochemistry was used. A moderate number of VAChT-immunoreactive (IR) nerve terminals were distributed between the acini, whereas only single cholinergic nerve fibres innervated the interlobular connective tissue. VAChT-positive nerve fibres supplying the endocrine pancreas were found only occasionally. The pancreatic blood vessels and ducts system were devoid of VAChT-containing nerve endings. All intrapancreatic neurons studied showed immunoreactivity to VAChT, but intrapancreatic ganglia were not innervated with cholinergic nerve fibres. The colocalization of VAChT and TH or VAChT and SP was detected in distinct populations of nerve fibres localized amongst the acini, but not within the islet nor in the connective tissue. Single VAChT-IR nerve terminals co-expressing NPY were distributed around the acini, islets as well as in the connective tissue septa. A moderate number of VAChT-IR/VIP-IR nerve endings were located in the exocrine pancreas, whereas the islets and connective tissue were innervated with VAChT/VIP-containing nerve fibres only occasionally. In the vast majority of VAChT-positive intrapancreatic perikarya the presence of TH was additionally found. A moderate number of VAChT-IR intrapancreatic perikarya co-expressed NPY, SP or VIP. The results of the present study demonstrate species-dependent cholinergic innervation pattern of the pancreas of the sheep. The co-localization of VAChT with the neuropeptides suggests the existence of functional interactions influencing the ovine pancreas (mainly exocrine) activity.     

Immunoreactivity to the pancreatic polypeptide family in the nervous system of the adult human blood fluke,Schistosoma mansoni

Summary The presence and distribution of neuropeptides belonging to the pancreatic polypeptide family have been demonstrated by an indirect immunofluorescence technique in the nervous systems of adult male and female Schistosoma mansoni. Seven antisera of differing regional specificity to pancreatic polypeptide (PP), peptide YY (PYY) and neuropeptide Y (NPY) were employed on both whole-mount and cryostat-sectioned material. Positive immunoreactivity (IR) was obtained with all antisera except an N-terminally-directed antiserum to NPY. In the CNS, immunoreactivity was restricted to cell bodies and nerve fibres in the anterior ganglia, central commissure and dorsal and ventral nerve cords of both sexes, whereas, in the PNS, positive-IR was present in the plexuses innervating the subtegumental musculature and the oral and ventral suckers. Intense immunoreactivity was observed in a plexus of nerve fibres and cell bodies in the lining of the gynaecophoric canal and in fine nerve fibres innervating the dorsal tubercles of the male. In contrast, in the female, strong immunoreactivity was evident in nerve plexuses innervating the lining of the ovovitelline duct and in the wall of the ootype, but most notably in a cluster of cells in the region of Mehlis' gland. Results suggest that molecules with C-terminal homology to the PP-family are present in S. mansoni. These peptides would appear to be important regulatory molecules in the parasite's nervous system and may play a role in the control of egg production.     

Presence of two neuropeptides in the fusiform ganglion and reproductive ducts of Octopus vulgaris: FMRFamide and gonadotropin-releasing hormone (GnRH)

We have found evidence of FMRFamide-like and cGnRH-I-like immunoreactivity in the central nervous system (CNS) and in the reproductive ducts of both female and male cephalopod Octopus vulgaris. Cell bodies and fibers were immunolocalized in the fusiform ganglion from which the nerves that reach the female and male reproductive ducts arise. FMRFamide-like and cGnRH-I-like immunoreactive nerve endings were present in the oviduct, and in the oviducal gland of the female and in the seminal vesicle of the male. The GnRH-like peptide from the reproductive ducts has been partially characterized by HPLC. The retention time of the Octopus vulgaris GnRH-like peptide was similar to the retention time of cGnRH-I. Based on these observations we suggest that FMRFamide-like and a novel GnRH-like peptide are involved in the control of reproductive ducts of Octopus vulgaris. One possibility is that the peptides affect gamete transport. Another possibility is that they regulate secretory products such as mucus and mucilaginous substances from the oviducal gland and the seminal vesicle. Our data provide further evidence to support the hypothesis of the existence of a central and peripheral peptidergic control of reproduction of Octopus vulgaris.     

Nitroxidergic elements in the digestive system of Mactra chinensis and Spisula sachalinensis (Mollusca: Bivalvia: Mactridae)

Localization and morphology of NO-ergic elements in the digestive system of bivalve molluscs Mactra chinensis and Spisula sachalinensis were studied using histochemical technique [1] for detection of NADPH-diaphorase (EC 1.6.99.1) [1]. The NO-producing elements were revealed in all parts of the digestive system of the studied animals. NADPH-diaphorase was found in cells of several morphological types as well as in nerve plexuses. The most abundant in the digestive tract parts of the studied molluscs were intraepithelial nerve cells of the “open” type, whose thin apical process is directed towards the gut lumen. Subepithelial NO-ergic neurons were revealed in stomach and crystalline style sac of Mactra chinensis. Besides, diformazan granules are present in brush-border epitheliocytes of the major and secondary ducts of the digestive gland as well as in cells of digestive tubules of this gland. All studied parts were found to contain basiepithelial and subepithelial NO-ergic nerve fibers forming networks of various densities from, most commonly, loose to dense plexuses particularly developed in labia, esophagus, and gut of the studied molluscs.     

Comparative characteristics of adrenergic innervation of the cerebrospinal arteries of vertebrates and man

Adrenergic innervation of the cerebrospinal arteries in redeye, frog, tortoise, hen, sea-gull, guinea-pig, rabbit, cat, dog and man has been studied by means of fluorescent-histochemical method. In all the animals there is a similar principle of innervation. The nervous apparatus is revealed as continuous integral plexuses. In the process of historical development the role of the nervous factor in regulation of the cerebrospinal circulation is increasing. As the innervational degree of the spinal arteries decreases, the vertebrates make the following line: mammals, birds, reptiles, amphibia, fishes. In all the animals, besides the fishes, the greatest concentration of the nervous fibers is revealed in the areas of the spinal cord thickenings.     

Ultrastructure of the nodes of Ranvier and their surrounding structures in the central nervous system

Summary The nodes of Ranvier and their surrounding structures have been studied by means of serial and single ultrathin sections of the frog's optic tract and diencephalon.The following aspects of the ultrastructure of the myelin sheath at the nodes are described: (a) the site and manner of termination of the compact myelin and glia-satellite cytoplasm; (b) the reflection of the glia-satellite cytoplasm at the node; (c) the formation of compact myelin during development; (d) the involvement of the glia-satellite cell in the metabolism and impulse conduction of the fiber.The nodes are surrounded by a considerable extension of the extracellular space — the perinodal extracellular space or perinodal matrix. The ground substance of the perinodal matrix consists of ill defined granules arranged in patches or in fibrillar or vacuolar manner. Microvilli-like protuberances of the glia and nervous processes emerge into the perinodal matrix. The shape and the volume of the perinodal extracellular space is determined using a reconstruction method from a series of sections through the node in diencephalon.In the diencephalon nerve endings show close contact with the node and its surroundings. These nerve endings contain synaptic vesicles, mitochondria and small opaque particles. Small opaque particles, up to the present not recognized as components of synapses, have been observed in a number of nerve endings in the diencephalon. The possibility is considered that such nervous configurations at the node could be involved in subliminal interactions between different neurons.Based on the ultrastructural data the concept of nodal apparatus is introduced as a working hypothesis. The nodal apparatus consists of the node, terminal compartments of the glia-satellite cell, the perinodal matrix, and the surrounding glia and nervous structures, which may be involved in the nodal activities. The structural pattern of such a nodal apparatus may vary in different parts of the central nervous system indicating the possibility of variation in the functioning of the corresponding nodes.This investigation was supported by a grant from the Medical Research Council, Canada (MA-1247).The author is very much indebted to Mrs. H. Rushforth for excellent technical assistance, to Mr. H. R. A. Meiborg, Groningen, for very skilful printing of the photographs and to Mr. Hoekstra, Groningen, who made the drawing of Fig. 8.     

Morphofunctional changes in the adrenergic innervation of the major cerebral arteries during bilateral electrostimulation of the locus coeruleus

The intramural adrenergic nervous apparatus of cerebral arteries was studied in adult rabbits after 3-10 sessions of electrical stimulation of locus coeruleus. The activity of nerve structures was determined by estimating the density of adrenergic perivascular plexuses and by semi-quantitative cytophotometry of changes in the catecholamine content of nerve varicosities. The stimulation was followed by a 28.2 +/- 1.5% increase in adrenergic innervation density. while catecholamine content in perivascular nerve structures displayed a tendency to decrease. The problem of central effects on cerebral blood flow autoregulation is discussed.