Distribution of FMRFamide-like immunoreactivity in the nervous system of the slug Limax maximus

Summary The distribution of FMRFamide-like immunoreactive neurons in the nervous system of the slug Limax maximus was studied using immunohistochemical methods. Approximately one thousand FMRFamide-like immunoreactive cell bodies were found in the central nervous system. Ranging between 15 m and 200 m in diameter, they were found in all 11 ganglia of the central nervous system. FMRFamide-like immunoreactive cell bodies were also found at peripheral locations on buccal nerve roots. FMRFamide-like immunoreactive nerve fibres were present in peripheral nerve roots and were distributed extensively throughout the neuropil and cell body regions of the central ganglia. They were also present in the connective tissue of the perineurium, forming an extensive network of varicose fibres. The large number, extensive distribution and great range in size of FMRFamide-like immunoreactive cell bodies and the wide distribution of immunoreactive fibres suggest that FMRFamide-like peptides might serve several different functions in the nervous system of the slug.     

Localization of stomatogastric IV neuron cell bodies in lobster brain

Summary The cell bodies of the inferior ventricular nerve (IVN) through-fibers of the lobster stomatogastric nervous system were located using cobalt chloride backfills and intracellular recordings. Following backfills of the IVN, two cell bodies in the supraesophageal ganglion (or brain) were stained with cobalt. These cells, each approximately 30 m in diameter, were located at the base of the IVN, just inside the connective tissue sheath surrounding the brain, and were identifiable on the basis of their close proximity to the IVN.In order to record from the cells, an in vitro preparation was made which included the cell bodies, their axons in the IVN and the stomatogastric nervous system. Intracellular recordings showed that the axons projected to the stomatogastric ganglion and made synaptic connections onto identified neurons. The axon trajectories and synaptic connections correlated with those previously described for the IVN through-fibers using extracellular stimulation and recording techniques.Abbreviations IVN inferior ventricular nerve - SN stomatogastric nerve     

Total numbers of neurons in myenteric ganglia of the guinea-pig small intestine

Two techniques that are thought to stain all of the neurons in the myenteric ganglia of the intestine are NADH diaphorase histochemistry and immunhistochemistry using a nerve cell body antiserum. However, this assumption has never been directly verified. In the present study myenteric ganglia of the guinea-pig ileum were prepared as whole-mounts and stained with either of these techniques. All nerve cells that could be identified in the whole-mounts were counted. The whole-mounts were then embedded flat in resin and serially sectioned at 1 m. Nerve cells were identified and counted from the serial sections, and the data compared to those obtained from the whole-mounts. NADH diaphorase histochemistry did not reveal all the neurons at incubation times that gave selective staining. In contrast, nerve cell body antiserum stained the entire neuronal population. To determine the total number of nerve cell bodies/ganglion and the proportion of nerve cell bodies with calbindin immunoreactivity, whole-mounts that had been processed for calbindin immunohistochemistry were serially sectioned and reconstructed. The total number of neurons per myenteric ganglion was 105±10 (SE). Calbindin-immunoreactive neurons comprised about 20% of the myenteric neurons, which is considerably less than previous estimates, because previously the total population has been underestimated. The spatial density of myenteric neurons in the undistended ileum of the guinea-pig is 17300 nerve cells/cm².     

Glutamate-immunoreactivity in the trigeminal and dorsal root ganglia, and intraspinal neurons and fibres in the dorsal horn of the rat

Summary Putative aspartergic and glutamatergic sensory neurons in the rat were identified by autoradiography and immunocytochemistry respectively. Approximately 3% of large L₄ dorsal root ganglion neurons (diameter 18–52 m) accumulated radiolabelled aspartate, whereas all satellite glia had high affinity for the amino acid. Glutamate-immunofluorescent (Glu-FITC) dorsal root ganglia neurons comprised 38.3% at S₁, 35.6% at L₂ 33.9% at C₅ and 28.8% at T₆. Numbers of immunoreactive neurons were higher with the more sensitive peroxidase-anti-peroxidase (Glu-PAP) method; and the cell counts totalled 42% (S₁), 41.2% (L₄), 35% (C₅) and 34.6% (T₆). The trigeminal ganglion (TG) contained 24% Glu-FITC and 32.3% Glu-PAP positive cells. The majority of glutamate-immunoreactive sensory neurons were small, ranging from 10–35 m with median diameters of 17.5m (C₅), 21m (S₁), 24.2m (TG) and 28.5 m (L₂). It is evident therefore, that a subgroup of class B cells are glutamatergic. Glutamate immunoreactivity in the spinal cord was similar in all segments and was localized in the superficial lamina and substantia gelatinosa of the dorsal horn. Stained interneurons were located among the immunoreactive fibres. The dorsolateral funiculus contained dense plexus of immunoreactive fibres which increased in prominence after intraperitoneal injection of L-glutamate, but penetration of exogenous glutamate into the grey matter was limited. Instead, the meninges and basal layers of the spinal blood vessels were intensely immunoreactive. The studies describe the subtypes of acidic amino acidergic neurons and relates the immunohistochemistry to a functional subclass.     

Distribution of FMRFamide-like immunoreactive neurons in the central nervous system of the snail Helix pomatia

Summary The distribution of FMRFamide-like immunoreactive (FLI) neurons and their morphological characteristics have been investigated in the central nervous system of the snail, Helix pomatia L. Approximately phageal ganglion complex. More than 50% of the FLI neurons were located in the cerebral ganglia. The FLI neurons could be divided into four groups according to size: (i) giant neurons (over 100 m); (ii) large neurons (80–100 m); (iii) medium-sized neurons (40–70 m); (iv) small neurons (12–30 m). They were distributed i) in groups or clusters, typical of small neurons and ii) in solitary form or in groups comprising 2–3 cells, typical of large and giant neurons. Giant and large neurons revealed only limited arborizations in the neuropil, but rich branching towards and in the peripheral nerves. Some of the small neurons had extensive arborizations of varicose fibers in the neuropil. They may therefore play some role in integratory processes. Varicose FLI fibers were visualized in the cell body layer of the different ganglia, and in the neural sheath of both the ganglia and the peripheral nerves. We propose a multifunctional involvement of FLI neurons and FMRFamide-like neuropeptides in the Helix nervous system: (i) a synaptic or modulatory role in axo-axonic interactions in the neuropil; (ii) a direct influence on neuronal cell bodies in the cortical layer, (iii) innervation of different peripheral organs; and (iv) remote neurohormonal control of peripheral events through the neural sheath.     

Calbindin-immunopositive cells are cholinergic interneurons in the myenteric plexus of rabbit ileum

The 28-kDa calcium-binding protein (calbindin) is a widely studied neuronal marker in the enteric nervous system of numerous species. Calbindin has previously been detected in myenteric neurons of rabbit ileum in which 3% of all myenteric neurons are calbindin-immunopositive. We have studied the detailed morphology and chemical coding of calbindin-immunopositive neurons in this segment of the gut. We have found calbindin immunoreactivity in both strongly and weakly stained neurons. Of these, the strongly immunoreactive neurons belong to the Dogiel type I category. These neurons project only to other ganglia and primary strands of the plexus and their processes never run to the muscle or mucosal layers. The neurons within this group are 29.5±6.6 m in length and 14.7±3.8 m in width. The second smaller group of immunoreactive cells (27%) label faintly and have different morphological properties. They are characterized by their round medium-sized cell bodies (long axis: 24.4±5.2 m; short axis: 15.5±2.9 m) and do not exhibit immunoreactivity either in their dendrites or in their axonal processes. Double-label studies show that all calbindin-immunopositive neurons lack immunoreactivity for nitric oxide synthase, vasoactive intestinal peptide and substance P but all are immunoreactive for the synthesizing enzyme of acetylcholine, choline acetyltransferase. Thus, populations of neurons containing calbindin are cholinergic interneurons in the myenteric plexus of rabbit ileum.This study was supported by grant OTKA T 34160     

Immunocytochemistry of GABA in the antennal lobes of the sphinx moth Manduca sexta

Summary The ganglionated plexus of the trachea of mice was studied quantitatively with a histochemical method that stains electively the ganglion nerve cells in whole-mount preparations. The plexus lies exclusively over the muscular part of the trachea, dorsal to the muscle itself, and it varies considerably in pattern and extent between individual animals. In young adult mice the plexus contains on average 235 neurons, occurring singly or gathered in packed ganglia. The ganglion neurons are relatively small, the profile area of three quarters of them measuring between 150 and 275 m² with an average of 251 m². In ageing mice the average number of ganglion neurons is the same as in young animals; however, cell sizes are markedly increased, the average being 341 m². Among the ultrastructural features of the ganglia, is a capsule (perineurium) of very regular structure, the presence of collagen, capillaries and myelinated axons inside the ganglia, and the presence of only few and short dendrites, some of which are abutted by synapsing nerve endings.     

Neuropeptide distribution in the cervico-thoracic paravertebral ganglia of the cat with particular reference to calcitonin gene-related peptide immunoreactivity

Summary Paraffin sections of cervical and upper thoracic paravertebral ganglia of the cat were investigated by immunohistochemistry using antisera directed against calcitonin gene-related peptide (CGRP). The relationships of CGRP-immunoreactive structures to those exhibiting immunoreactivity to antisera against other regulatory peptides and dopamine--hydroxylase (DBH), respectively, were studied in consecutive sections. Singly scattered CGRP-immunoreactive neuronal perikarya were observed in the superior and middle cervical ganglia as well as in the stellate ganglion. These neurons also displayed immunoreactivity to vasoactive intestinal polypeptide (VIP), and some additionally exhibited faint substance-P immunoreactivity. DBH- and neuropeptide Y-immunoreactive ganglion cells were not identical with CGRP-immunoreactive neuronal cell bodies.According to the immunoreactive properties of varicosities, which abut on CGRP/VIP-immunoreactive perikarya, three types of CGRP/VIP-immunoreactive ganglion cells could be distinguished: (1) CGRP/VIP-immunoreactive neurons being surrounded by somatostatin-immunoreactive nerve fibers, (2) neurons being approached by both DBH- and met-enkephalin-immunoreactive varicosities, and (3) neurons receiving both DBH- and neurotensin-immunoreactive fibers. The stellate and upper thoracic ganglia harbored clusters of intensely VIP-immunoreactive somata, which lacked CGRP-immunoreactivity. Fine somatostatin-immunoreactive and coarse CGRP-immunoreactive fibers were distributed within these clusters, whereas patches of neurotensin-immunoreactive fibers were complementarily arranged. At all segmental levels investigated, a few postganglionic neurons were approached by both CGRP-immunoreactive and substance P-immunoreactive varicosities, but lacked a VIP-immunoreactive innervation. Therefore, CGRP/substance P-immunoreactive fiber baskets appeared rather to be of extraganglionic origin than to emerge from intraganglionic CGRP/VIP/SP neurons. CGRP-immunoreactive cell bodies or fibers were absent in clusters of small paraganglionic cells, but some of the solitary paraganglionic cells displayed CGRP-immunoreactivity. Our findings establish the presence of CGRP-immunoreactivity in a population of sympathetic neurons in the cat. A highly differentiated, segment-dependent organizational pattern of neuropeptides in cervico-thoracic paravertebral ganglia was demonstrated.Supported by Deutsche Forschungsgemeinschaft grant He 919/6-2     

Fine structure,origin, and distribution density of the autonomic nerve endings in the tarsal muscle in the eyelid of the mouse

Summary The fine structure, origin, and distribution density of the autonomic nerve endings in the tarsal muscle of the mouse were studied by histochemistry and electron microscopy. With histochemical methods, the fine nerve plexus in the normal muscle shows both catecholamine-positive varicose fibers and acetylcholinesterase-active varicose fibers. The former are distributed more densely than the latter. After superior cervical ganglionectomy, the catecholamine-positive fibers disappear, while after pterygopalatine ganglionectomy, the acetylcholinesterase-active fibers vanish. In electron micrographs, the varicosities appear as expansions containing many synaptic vesicles. The axonal expansions partly lack a Schwann sheath and directly face the pinocytotic vesicle-rich zones of the smooth muscle cells. A relatively wide space, 0.1 to 1.0 m in width, lies between nerve expansion and muscle cell. The expansions can be classified into two types: Type I having small granular synaptic vesicles, and Type II having agranular vesicles instead of small granular synaptic vesicles. Type I undergoes degeneration after superior cervical ganglionectomy, while Type II degenerates after pterygopalatine ganglionectomy. This indicates that Type I corresponds to the synaptic ending of the adrenergic fiber originating from the superior cervical ganglion, and Type II to the synaptic ending of the cholinergic nerve fiber derived from the pterygopalatine ganglion. Type I is more frequent (88/10⁴ m² area of muscle) than Type II (17/10⁴ m²).     

Excitatory synapses of blue crab gastric mill muscles

Summary Physiological and ultrastructural studies were made of neuromuscular synapses in stomach muscles, especially two gastric mill muscles of the blue crab innervated by neurons of the stomatogastric ganglion. These muscles depolarized and contracted with application of glutamate, but not acetylcholine, whereas the dorsal dilator muscles of the pyloric region depolarized and contracted in acetylcholine, but not in glutamate. Large excitatory postsynaptic potentials (EPSP's) of 5–20 mV were recorded in the gastric mill muscles. At low frequencies of activation, individual synapses released on average about 2 quanta of transmitter for each nerve impulse. Facilitation of EPSP's after a single nerve impulse could be detected for at least 10 s. Synapses were found on enlarged terminals of the motor axon; their contact areas ranged from 0.2 m² up to 3 m². Both electron-lucent, round synaptic vesicles and dense-cored vesicles occurred near these synapses. A possible correlation between contact area of a synapse and output of transmitter, is discussed.Supported by grants from the National Research Council of Canada and the Muscular Dystrophy Association of Canada to H.L. Atwood and C.K. Govind. We thank Kazuko Hay, Eva Yap-Chung and Irene Kwan for technical assistance with electron microscopy and reconstruction of nerve terminals from micrographs     

Somatostatin-like immunoreactivity in non-pyramidal neurons of the human entorhinal region

Summary The distribution of somatostatin-immunoreactive cells and processes throughout the human entorhinal region and subjacent white matter was examined either by the unlabelled antibody-enzyme method or by the avidin-biotin method. The brain slices were obtained at autopsy with a short post-mortem delay. The majority of somatostatin immunoreactive nerve cells was found in the inner principal layer and subjacent white matter. In addition, individually scattered immunoreactive neurons were observed in both the outer principal layer and lamina dissecans. The immunoreactive perikarya varied in shape and ranged in size from 10 to 30 m. Without exception the neurons could be classified as belonging to the group of non-pyramidal neurons. Each neuron gave rise to a few thick dendrites and a thin axon with a beaded appearance. In the adult human brain, the pattern formed by lipofuscin granules deposited in the nerve cells can be considered characteristic for the type of the neuron. Therefore, immunoreactive perikarya were documented, destained of chromogen and restained to demonstrate lipofuscin pigment and basophilic substance. It became evident from these studies that the previously immunoreactive cells were characterized by a large rounded and eccentrically located nucleus, sparse basophilic substance and, in most cases, a lack of lipofuscin granules. A few of the immunoreactive cells were laden with coarse pigment granules. The findings permit classification of entorhinal somatostatin-immunoreactive neurons as either non-pigmented or pigment-laden non-pyramidal neurons.Dedicated to Prof. Dr. J. Lang, Würzburg, on the occasion of his 65th birthdayA portion of the results has been presented at the annual meeting of the European Neuroscience Association 1986 in Marseille, France (Friederich-Ecsy et al. 1986)     

Immunohistochemical localization of neuropeptide Y in the guinea pig medulla oblongata

Summary The immunohistochemical localization of neuropeptide Y (NPY) was correlated with those of dopamine--hydroxylase (DBH) and vasoactive intestinal polypeptide (VIP) by mapping serial 7 m paraffin sections at three levels of the guina pig lower brainstem: a) area postrema, b) dorsal motor nucleus of the vagus, and c) nucleus prepositus of the hypoglossal nerve. Based on differences in transmitter expression, three populations of NPY-immunoreactive (IR) neurons were distinguished: NPY-IR catecholaminergic cells (NPY/CA), NPY-IR VIP-ergic cells (NPY/VIP), and NPY-IR cells which were not reactive to either DBH or VIP. Within these populations, size differences among neurons in characteristic locations allowed differentiation among the following subpopulations: NPY/CA neurons in the lateral reticular nucleus — magnocellular part (mean neuronal size 538 m²) and parvocellular part (318 m²)-, in the vagus-solitarius complex (433 m²), and in the dorsal strip (348 m²); NPY/VIP neurons in the vagus-solitarius complex (368 m²) and in the nucleus ovalis (236 m²). Apart from scattered NPY-IR cell bodies in the regions listed above, NPY-IR cell bodies in the lateral portion of the nucleus solitarius and in the caudal part of the spinal nucleus of the trigeminal nerve did not exhibit IR to either DBH or VIP. NPY-IR neurons in the area postrema occurred too infrequently for co-localization studies. The differential distribution of heterogeneous NPY-IR cell subpopulations may reflect the involvement of NPY in a variety of neuronal functions.Supported by the Deutsche Forschungsgemeinschaft, grant He 919/6-1     

The endogenous development of four new species of Isospora Schneider, 1881 (Apicomplexa: Eimeriidae) from Australian geckos

Four new species of Isospora are described from Australian geckoes. Isospora gehyrae n. sp. from Gehyra cf. variegata in South Australia have 18.5-22.5×17.5–20.0 m oöcysts with 10.0-12.5×7.5-9.0 m sporocysts; endogenous stages develop in the host cell cytoplasm. Of the two species found in Heteronotia binoei from northern Queensland, Isospora cytoheteronotis n. sp., with oöcysts of 20.0-26.0×17.5-25.0 m and sporocysts of 10.0-13.5×7.5-11.5 m, undergoes endogenous development in its host cell cytoplasm, whereas I. nucleoheteronotis n. sp., with oöcysts of 17.5-22.5×17.5-21.5 m and sporocysts of 9.0-12.5×6.5-10.0 m, develops in the host cell nucleus. I. oedurae n. sp. from Oedura rhombifer in northern Queensland has oöcysts of 22.5-25.0×22.5-24.0 m and sporocysts of 12.5-14.0×7.5-11.5 m, and undergoes endogenous development in its host cell nuclei.     

Substance P in the suprachiasmatic nucleus of the rat: an immunohistochemical and in situ hybridization study

Using a biotin-streptavidin-horseradish peroxidase (HRP) immunohistochemical technique the distribution of substance P-immunoreactive neuronal elements was investigated in the rat suprachiasmatic nucleus (SCN). Substance P-immunoreactive nerve fibres and varicosities were distributed throughout the suprachiasmatic nucleus, with the largest accumulation in its ventral part. Because this location overlaps with the innervation of retinal afferents, the distribution and density of substance P-immunoreactive fibres in bilaterally enucleated rats were compared to normal rats. The density of substance P-immunoreactive fibres and nerve terminals in the ventral part of the suprachiasmatic nuclei was reduced in the rats with bilateral destruction of the optic nerves, whereas the density of fibres and nerve terminals in the dorsal part as well as other retinal target areas in the thalamus and mesencephalon was unaffected. In rats pretreated with an intraventricular injection of colchicine several substance P-immunoreactive perikarya were identified in the suprachiasmatic nucleus. The immunoreactive neurons, measuring 9.7 m±1.1 m in diameter, were frequently observed in the central core of the nucleus and to a lesser extent in the dorsomedial and ventrolateral subparts. Using in situ hybridization histochemistry pre-protachykinin-A mRNA was found in the same part of the SCN indicating that synthesis of substance P takes place in SCN neurons. Using a double immunohistochemical approach applying diaminobenzidine and benzidinedihydrochloride as chromagens substance P-, vasoactive intestinal peptide (VIP)-, and vasopressin/neurophysin-immunoreactivities were identified in the same brain section. The substance P-immunoreactive perikarya constituted a separate population of SCN neurons, which were not vasopressin-, neurophysin- or VIP-immunoreactive. Taken together, these observations show that substance P is contained in the retinohypothalamic pathway and within a group of SCN cell bodies, indiating that substance P may play a role in the generation and entrainment of circadian rhythmicity.     

Polarized distribution of γ interferon-stimulated MHC antigens and transferrin receptors in a clonal cell line isolated from Fisher rat thyroid (FRT cells)

Summary The fine structure of single identified muscle fibers and their nerve terminals in the limb closer muscle of the shore crab Eriphia spinifrons was examined, using a previous classification based on histochemical evidence which recognizes a slow (Type-I) fiber and three fast (Type-II, Type-III, Type-IV) fibers. All four fiber types have a fine structure characteristic of crustacean slow muscle, with 10–12 thin filaments surrounding each thick filament and sarcomere lengths of 6–13 m. Type-IV fibers have sarcomere lengths of 6 m while the other three types have substantially longer sarcomeres (10–13 m). Structural features of nerve terminals revealed excitatory innervation in all four fiber types but inhibitory innervation in Type-I, Type-II, and Type-III fibers only. Thus fibers with longer sarcomeres receive the inhibitor axon but those with shorter sarcomeres do not. Amongst the former, synaptic contact from an inhibitory nerve terminal onto an excitatory one, denoting presynaptic inhibition, was seen in Type-I and Type-II fibers but not in Type-III and Type-IV fibers. Inhibitory innervation of the walking leg closer muscle is therefore highly differentiated: some fibers lack inhibitory nerve terminals, some possess postsynaptic inhibition, and some possess both postsynaptic and presynaptic inhibition.     

Ultrastructure of the osphradium of Aplysia californica

Summary The osphradium of Aplysia californica, a sensory organ, is a small yellow-brown epithelial patch located in the mantle cavity immediately anterior to the rostral attachment of the gill. Scanning electron microscopy reveals a round ellipsoid structure of 0.6–1 mm in diameter with a central, occasionally folded, sensory epithelium. The central area is covered with microvilli and surrounded by a densely ciliated epithelium. Transmission electron micrographs show that the columnar supporting cells in the sensory epithelium contain an abundance of apical pigment granules and microvilli. Between the epithelial-supporting cells, the putative sensory elements consist of thin neurites (0.4–1.5 m in diameter) that reach the sea-water side of the osphradium. The neurites contain many neurotubules, mitochondria, vesicles and cilia in their apices. The nerve endings originate from cell bodies up to 40 m below the epithelium or in the osphradial ganglion itself, as revealed by electron microscopy and retrograde labeling with Lucifer yellow. There appear to be two populations of putative sensory cells, a large population of heavily stained cell bodies 4–10 m in diameter and a few scattered cells of large diameter (25–60 m). Following lanthanum impregnation, septate junctions can be seen between all types of cells in the epithelium, 3–5 m below the sea-water surface. This study provides new information for further investigation of osmo- and mechanosensation in Aplysia californica.     

Substance P-like immunoreactivity in the trigeminal ganglion

Summary The trigeminal ganglion of rat and guinea pig was studied for the presence of immunoreactive substance-P using fluorescence, light and electronmicroscopy. In untreated animals substance P containing cells, with a diameter of 15 to 50 m, were distributed throughout the ganglion and comprised 10–30% of all ganglion cells. Colchicine, injected intraventricularily to inhibit intra-axonal transport, had no effect on the number of substance P cells; but when the drug was injected directly into the posterior root of the ganglion, the proprotion of these cells increased to as much as 50%. In the electron microscope, immunoreactive substance-P was confined to ganglion cells classified as B type according to the arrangement of subcellular organelles, and to unmyelinated nerve fibers. Subcellularily the immunoreactivity appeared in cytoplasmic vesicles, as well as dispersed in the nerve fibers and the perikarya of neurons. The great number of substance P immunoreactive ganglion cells suggests that they do not comprise a well defined subpopulation of the B-cells.However, the immunoreactivity was restricted to a distinct ultrastructural type of neurons with unmyelinated nerve fibers, suggesting that they also may share some distinct functions.     

Neurochemically similar myenteric and submucous neurons directly traced to the mucosa of the small intestine

Summary Antisera to neuropeptide Y (NPY) gave an intense immunohistochemical reaction of certain nerve cells in the myenteric and submucous plexuses of the guinea-pig small intestine. Each nerve cell had up to 20 branching, tapering processes that were less than 50 m long and a long process that could be followed for a considerable distance. This morphology corresponds to that of the type-III cells of Dogiel. The long process of each myenteric cell ran through the circular muscle to the submucosa, and in most cases the process could be traced to the mucosa. The submucous nerve cell bodies also had processes that extended to the mucosa. These cell bodies, in both plexuses, also stained with antisera raised against calcitonin generelated peptide (CGRP), cholecystokinin (CCK), choline acetyltransferase (ChAT) and somatostatin (SOM), but did not stain with antibodies against enkephalin, substance P or vasoactive intestinal peptide. Thus, it has been possible for the first time to trace the processes of chemically specified neurons through the layers of the intestinal wall and to show by a direct method that CGRP/CCK/ChAT/NPY/ SOM myenteric and submucous nerves cells provide terminals in the mucosa.     

Electron-microscopic characterization of adrenergic axon terminals in the diencephalon of the rat

Summary The fine structure of adrenergic axon terminals was examined in the paraventricular nucleus of the thalamus (PNT) and in the hypothalamic arcuate nucleus-median eminence (ARC-ME) complex by use of phenylethanolamine-N-methyl transferase (PNMT) immunocytochemistry. In the PNT, immunoreactive terminals formed a dense and well-circumscribed plexus. In the ARC, labeled varicosities were less numerous and more evenly distributed. In the ME, they were scarce and confined to the inner zone. In all these areas, the diameter of immunoreactive varicosities ranged between 0.2 and 1.3 m; in the ME and in the transitional zone between the ARC and the ME, a population of larger boutons (>2 m) was also visible. All immunoreactive varicosities exhibited densely packed small, clear vesicles associated with a few large granular vesicles. In the PNT and the ARC, but not in the ME, they formed synaptic contacts with dendritic elements and were occasionally apposed to neuronal cell bodies. These axo-somatic appositions showed no junctional specializations. In the ME and transitional zone, immunoreactive terminals were frequently juxtaposed to, and occasionally established differentiated synaptic contacts with, tanycytes. These data support a transmitter role for adrenaline in the diencephalon and suggest that adrenaline plays a role in hypothalamo-hypophysiotropic regulation through interactions with neural and glial elements.     

Flow cytometric analysis of chromosomes and cells using a modified BrdU-hoechst method

Summary The sensory innervation of 46 poles of long chain intrafusal muscle fibers was studied histochemically by staining for NADH-TR in periodic, 8 m thick transverse sections of cat muscle spindles. Each long chain fiber carried terminals of the primary sensory axon, and 23 of the fiber poles also displayed secondary sensory endings. With the NADH-TR reaction there was no apparent difference in the cross-sectional appearance of sensory endings on the long chain and on other nuclear chain fibers. However, the contact area between the secondary endings and the muscle fiber tended to be shorter on the long chain than on the neighboring chain fibers of shorter polar length. This was also the case for one long chain fiber in which the sensory innervation was examined in serial, 1 m thick sections stained with toluidine blue. Discharges of the secondary sensory axons in cat spindles may be affected more by contraction of the shorter nuclear chain fibers than by activation of the long chain fibers.