Distribution Pattern Of Fibers Research Articles

Histo‐and Cytochemical Studies on the Distribution of Acetylcholinesterase‐positive Nerve Fibers in the Goat Adrenal Gland

The distribution patterns of acetylcholine esterase positive nerve fibers in the goat adrenal gland is described. Some positive cells are observed within the capsule. Terminals were identified in both the medulla and the cortex of the gland.

Met]enkephalin-arg 6-gly 7-leu 8-immunoreactive nerves in guinea-pig and rat lungs: Distribution, origin, and co-existence with vasoactive intestinal polypeptide immunoreactivity

[Met]Enkephalin-Arg 6-Gly 7-Leu 8 is an endogenous opioid peptide, first isolated from the bovine adrenal medulla. Because this octapeptide is specifically contained in the amino acid sequence of preproenkephalin A but not in other opioid precursors like preproopiomelanocortin or preproenkephalin B, [Met]enkephalin-Arg 6-Gly 7-Leu 8 has been regarded as a specific marker for preproenkephalin A and its derivatives. In this study, we examined the occurrence and origin of [Met]enkephalin-Arg 6-Gly 7-Leu 8-immunoreactive nerves in the guinea-pig and rat lung by immunohistochemical techniques, using a specific antiserum against this peptide. In addition, we investigated the possible co-existence of [Met]enkephalin-Arg 6-Gly 7-Leu 8 and vasoactive intestinal peptide immunoreactivity in neuronal elements of the respiratory tract. In both species, [Met]enkephalin-Arg 6-Gly 7-Leu 8 immunoreactivity was localized in nerve fibers chiefly distributed to the trachea and major bronchi, where they were prevalent in smooth muscle bundles, in the lamina propria, around airway glands, and in the walls of pulmonary vessels, but were absent in airway epithelium. Slight differences in the distribution pattern of immunoreactive nerve fibers were noted between the two species: immunoreactive nerve fibers in the smooth muscle bundles were much more abundant in guinea-pigs than in rats, while those in the mucous glands were richer in rats than in guinea-pigs. Neither chemical sympathectomy by 6-hydroxydopamine, nor chemical sensory denervation by capsaicin, changed the density or distribution of [Met]enkephalin-Arg 6-Gly 7-Leu 8-immunoreactive nerve fibers in the airway, suggesting an intrinsic source for these nerve fibers. Colchicine injection into the tracheal wall, to promote the accumulation of neuropeptides in nerve cell bodies, led to the visualization of [Met]enkephalin-Arg 6-Gly 7-Leu 8 immunoreactivity in some neuronal cell bodies within airway ganglia. Immunostaining for [Met]enkephalin-Arg 6-Gly 7-Leu 8 and for vasoactive intestinal polypeptide on serial adjacent sections of airway ganglia obtained from colchicine-treated tracheae, demonstrated the co-existence of these immunoreactivities in a population of nerve cell bodies in these ganglia. The immunohistochemical localization of immunoreactive [Met]enkephalin-Arg 6-Gly 7-Leu 8 in nerve elements in guinea-pig and rat lungs provides a morphological basis for the possibility that pre-proenkephalin A-related opioid peptides may have a neuromodulatory role in mammalian airways and pulmonary vessels.

Distribution of serotonin-like immunoreactive nerves in major cerebral arteries of rabbit: an immunohistochemical study.

We studied the distribution pattern of serotonin-like immunoreactive nerve fibers in the major cerebral vessels of rabbit by an indirect immunofluorescence technique using whole-mount stretch preparations. The density of serotonin-like immunoreactive nerve fibers was greater in vessels of the posterior part of the circle of Willis compared with that in the anterior part. This is in contrast to most of the observations reported previously regarding adrenergic, cholinergic, and peptidergic innervation of the circle of Willis.

Chemoanatomical organization of the noradrenergic input from locus coeruleus to the olfactory bulb of the adult rat

The locus coeruleus contains noradrenergic neurons which project widely throughout the CNS. A major target of locus coeruleus projections in the rat is the olfactory bulb (Shipley et al.: Brain Res. 329:294-299, '85) but the organization of the projections within the bulb has not been systematically examined. In this study, the laminar distribution and densities of locus coeruleus-noradrenergic fibers in the main and accessory olfactory bulbs were determined with anterograde tracing and immunocytochemical techniques. Following iontophoretic injections of 1% wheat germ agglutinin-horseradish peroxidase into the locus coeruleus, the densest anterograde label in the accessory olfactory bulb was observed in the external plexiform layer, granule cell layer, and especially in the internal part of the mitral cell layer. Virtually no label was observed in the glomerular layer. In the main olfactory bulb, labelled axons were observed in the granule cell layer, in the internal and external plexiform layers, occasionally in the mitral cell layer, and least often in the glomerular layer. Noradrenergic fibers in the olfactory bulb were identified by using immunocytochemistry with an antibody to dopamine-beta-hydroxylase. Laminar patterns and densities of noradrenergic innervation were determined with quantitative image analysis. In the accessory olfactory bulb, the densest innervation was in the innermost portion of the mitral cell layer followed by the granule cell layer, the superficial part of the mitral cell layer, and the external plexiform layer. The density of fibers in the glomerular layer was least. The laminar pattern of noradrenergic fiber distribution in the main olfactory bulb was similar to that in accessory olfactory bulb. The present studies demonstrate that locus coeruleus-noradrenergic fibers terminate preferentially in the internal plexiform, granule cell, and external plexiform layers. This suggests that the major influence of the locus coeruleus input to both the main and accessory the olfactory bulbs is on the predominant neuronal element in those layers, the granule cells. Additional studies are needed to resolve how this input influences specific olfactory bulb circuits.

Changes in properties of the medial gastrocnemius motor units in aging rats.

1. The properties of motor units were investigated in the medial gastrocnemius (MG) of old rats [27.5 +/- 1.6 (SD) mo old, n = 18]. Individual motor units were functionally isolated by ventral root fiber splitting and grading stimulus intensity. The muscle-unit portion of the motor unit was identified by the glycogen depletion method. The physiological properties of 77 motor units in 6 animals and the histological results of 7 slow-twitch (type S) muscle units were compared with data from motor units in the same muscle of middle-aged rats (12.8 +/- 1.6 mo old, n = 33). 2. The motor units were classified into four types of categories [FF (fast-twitch motor units with a fatigue index less than or equal to 0.5), FI (fast-twitch motor units with a fatigue index greater than 0.5 but less than 0.75), FR (fast-twitch motor units with a fatigue index greater than or equal to 0.75), S (slow-twitch motor units with a fatigue index greater than 0.75)] using the same criteria (i.e., presence or absence of the "sag" property and fatigability) used for middle-aged rats. No significant difference in the relative distributions of these unit types was detected, although the MG muscle in old rats exhibited a relatively high proportion of type S units and fewer type FR units. 3. The mean tetanic tensions for type FF + FI and FR units were significantly smaller than those in the middle-aged rats. On the other hand, type S motor units produced more tension than in the middle-aged rats. 4. The conduction velocity of motor axons was considerably slower in any unit type of old motor units, and the most marked change was found in type FR units. 5. The general morphological features of the old rat MG were fiber-type grouping, disseminated atrophic or angulated fibers, a decrease in the total number of muscle fibers, and an increase in the number of type I muscle fibers. The major distribution patterns of fibers of different types were the same as those in the middle-aged MG. 6. Seven type S units that produced large tetanic tension were depleted of glycogen in the muscle-unit portions. These units had a large innervation ratio compared with those in the middle-aged rats, whereas the mean cross-sectional area of muscle fibers and the calculated specific tension remained unaltered.(ABSTRACT TRUNCATED AT 400 WORDS)

Light and electron microscopic immunocytochemical analysis of the noradrenaline innervation of the rat visual cortex.

Immunocytochemistry with an antiserum against noradrenaline was used to examine the organization and morphology of noradrenergic axons in the rat visual cortex. Observations with the light microscope confirmed earlier reports concerning the distribution pattern of noradrenergic fibres, and provided some further clues about their intracortical organization. Particularly striking was the finding of fibres which followed an oscillating course within the boundaries of layers II-IV as they ran in the mediolateral direction. Examination of the morphological characteristics of noradrenaline-containing axon terminals in serial ultrathin sections has provided further evidence that the vast majority (87.6%) form conventional synapses in the visual and frontoparietal cortex, and has given clues about the postsynaptic elements involved in these synaptic contacts; they are, in decreasing frequency, spines, dendritic shafts of various diameters, and pyramidal and non-pyramidal somata. In addition, a few labelled terminals were visualized in close association with intracerebral capillaries.

On the distribution of elastic fibers in the filiform papillae of Suncus murinus.

The distribution of elastic fibers in the filiform papillae of 1, 2, 3, 4 and 5 week-old and 6 month-old Suncus (Suncus murinus; insectivora) was examined by both Weigert's resorcin-fuchsin method and ultrastructural means. In the adult Suncus (6 months old), elastic fibers in the connective tissue core of the papillae were aligned perpendicularly to the epithelial surface and formed a palisade-like structure which encircled the margin of each connective tissue core. This characteristic structure was restricted to the filiform papillae in the anterior half of the lingual dorsum. In the filiform papillae of the posterior half, elastic fibers were markedly reduced and the palisade-like structure was not present. This characteristic pattern of elastic fiber distribution was established by 3 weeks of age. These observations reveal a characteristic structure consisting of elastic fibers in the connective tissue core of the filiform papillae and the regional distribution of this structure in the tongue. This suggests that the function of the structure in the connective tissue core is to protect against mechanical stress in mastication. The regional distribution of this structure may reflect the difference of mechanical strength between the anterior and posterior of the tongue caused by tongue movement during mastication.

Cholinergic innervation of the main and the accessory olfactory bulbs of the rat as revealed by a monoclonal antibody against choline acetyltransferase.

The main and accessory olfactory bulbs (MOB and AOB) of the rat were immunohistochemically stained with a monoclonal antibody against choline acetyltransferase (ChAT) in order to know the difference in the distribution patterns of cholinergic fibers between these two structures. A few ChAT-immunoreactive cell bodies were found in the superficial and middle parts of the external plexiform layer (EPL) of the MOB, in the granule cell layer (GCL) of the MOB, and in the GCL of the AOB. The frequency in appearance of these cells was 0.9 cells/section in the MOB and 0.3 cells/section in the AOB. While the glomerular layer (GL) and the superficial part of the EPL were most densely innervated in the MOB, the internal plexiform layer received the richest innervation in the AOB. There were no immunoreactive structures in the olfactory nerve layer of the MOB and in the vomeronasal nerve layer and glomerular layer of the AOB. In addition to a relatively homogenous distribution of cholinergic fibers in the MOB and AOB, there were several foci of very dense network of immunoreactive fibers at the posterior level of the OB. These foci formed a part of the modified glomerular complex that was recently identified using 2-deoxyglucose method and was presumed to be related to suckling behaviour in the neonatal rat.

Distribution pattern of cell bodies and fibers with neurotensin-like immunoreactivity in the cat hypothalamus.

Neurotensin is widely distributed in the central and peripheral nervous systems. Extensive radioimmunoassay and immunohistochemical studies in rats show that the neurotensin immunoreactive perikarya and fibers are most prominent in the hypothalamus. Radioimmunoassay studies have suggested that the levels of neurotensin in the hypothalamus of cats may be six times higher than that of rats. We studied the distribution pattern of neurotensin immunoreactivity within the hypothalamus of the cat by avidin-biotin modification immunohistochemical methods: (1) to define its distribution pattern within the hypothalamus, and (2) to compare our findings with the patterns that have been described in rats. Results show that neurotensin immunoreactive cell bodies and fibers are most prominent in the rostral and intermediate regions of the cat hypothalamus. Cell bodies with neurotensin-like immunoreactivity are seen maximally in the medial preoptic region, the infundibular nucleus, and the lateral hypothalamus. The neurotensin positive fibers are dense in the periventricular regions of the entire rostro-caudal extent of the hypothalamus. This pattern of distribution of neurotensin immunoreactivity is similar to that described in rats. The suprachiasmatic nuclei of the cat hypothalamus, however, contained a significant number of neurotensin immunoreactive cell bodies, an observation not noted in the rat hypothalamus. The neurotensin immunoreactive neurons were more numerous in the lateral hypothalamus than has been reported in rats, but the paraventricular nucleus of the hypothalamus in cats contained fewer neurotensin immunoreactive perikarya. The presence of neurotensin immunoreactive perikarya in the suprachiasmatic nucleus and the apparent increase in the number of neurotensin immunoreactive neurons in the lateral hypothalamus may account for the increased levels of neurotensin reported in cats. Neurotensin has been speculated to play a role in nociception, thermoregulation, and control of arterial pressure by acting as a hormone or a neurotransmitter. Details of the pattern of colocalization of neurotensin with that of other neuropeptides and neurotransmitters will aid in our understanding of its role in these functions.

Organization and synaptic relationships of the projection from the primary sensory to the primary motor cortex in the cat.

It is known from previous studies that fibers originating from cells in area 2 of the cat primary somatosensory cortex project topographically to area 4 of the motor cortex and that they terminate preferentially in the caudal region of the cruciate sulcus. We examined this pathway to determine more precisely the distribution pattern of fibers and the laminar arrangement of axon terminals in the motor cortex. The recently developed technique of PHA-L staining enabled us to label anterogradely the axons that form this projection. Iontophoretic injections of PHA-L were made into the rostral bank of the ansate sulcus (area 2). After 7 days the cats were perfused and the tissue was processed immunohistochemically to stain the PHA-L filled fibers. Light microscopic examination revealed that a small cluster of cells in the sensory cortex gave rise to multiple foci of labeled axons in area 4. The labeled fibers formed columnlike arrays, which were located for the most part in the posterior bank of the cruciate sulcus and were separated by irregular intervals of cortex devoid of labeled fibers. Clusters of labeled fibers were also found in the anterior region of the cruciate sulcus in some of the animals. The dimensions of the labeled areas and the small number of cells that gave rise to each group of fibers suggested that axonal branches of cells within the injection site formed the multiple foci. Variations in the immunohistochemical staining enabled us to study the laminar distribution of sensory cortex axon terminals with the electron microscope. Whereas some PHA-L labeled terminals were found in the deep cortical layers, the majority (82%) were spread throughout layers I-III. Differences in the laminar distribution of sensory cortex afferents that formed axodendritic or axospinous synapses were noted. Synapses formed with dendritic shafts were relatively sparse (28%) and were confined to the superficial layers. Some of the more numerous axospinous synapses, which accounted for 72% of identified synapses, were found in layers V and VI, although most were in layers I-III. The distribution pattern of terminals showed little variation between columns in different areas of the motor cortex, including that in the anterior cruciate region. The pattern of termination of the sensory to motor cortex projection is discussed in relation to the physiological characteristics of this pathway.

Strain-specific development of the mossy fiber system in organotypic cultures of the mouse hippocampus

The postnatal development of the hippocampus of the inbred mice strains BALB/c, C57BL/6, and DBA/2 was studied in organotypic explant cultures using the roller-tube technique. In vivo, mice exhibit strain-specific mossy fiber distribution patterns. As a main result we found, that after cultivation of 3–4 weeks, similar strain-specific patterns became apparent in vitro, as visualized by a modified Timm staining. From this experiment we can conclude that a postnatal extrinsic influence cannot be the cause of the strain-specific hippocampal features.

The gelatinous fibres of Caesalpiniaceae

Twenty-seven species of Caesalpiniaceae were studied to compare the gelatinous fibres of root and stem wood. Species that possessed gelatinous fibres in root wood also possessed them in stem wood, but only two taxa showed the reverse condition. Gelatinous fibres did not exhibit an organ-dependent specificity in their transectional distribution. In roots, the gelatinous fibres generally differentiated immediately after initiation of secondary growth, whereas in most stems they differentiated considerably after the onset of secondary growth. The positive correlation detected previously between the distribution pattern, as well as the number of gelatinous fibres, and the eccentricity of the stem or root could not be verified. Even perfectly noneccentric roots and stems showed variations in the distribution pattern and number of gelatinous fibres. In roots, generally, all fibres were gelatinous, whereas in stems both gelatinous and normal fibres were present and showed different distributional patterns. All three types of gelatinous fibres (convolute, thick, and intermediate) recognised by earlier workers and based on the gelatinous layer were observed in this family. Gelatinous fibres of this family formed lignified, partially lignified, and nonlignified gelatinous layers. Differences were also noticed in the relative thickness of the gelatinous layer.

Serotonergic afferents to the rat olfactory bulb: II. Changes in fiber distribution during development

The present studies have defined the developmental time course and distribution patterns of serotonergic fibers in the main olfactory bulb (MOB) using immunocytochemistry, anterograde tracing and image analysis. The results indicate that the deployment of serotonergic fibers to the main olfactory bulb is essentially a postnatal event in the rat. During the first 4 d after birth, 5-HT fibers infiltrate and begin to arborize in the MOB. The density of fibers in each layer is sparse during this period, but increases rapidly. By postnatal day 8 all layers are much more heavily innervated by 5-HT fibers. The surge of fiber growth into all layers is rapid; the fibers arborize earlier at caudal than at rostral levels. This may be related to the increased metabolic activity that is reported to occur selectively in the caudal parts of the immature olfactory bulb. After the second postnatal week, 5-HT fiber density increases much more gradually in all layers except the glomerular layer; in the glomerular layer, 5-HT fiber density continues to increase rapidly. It is also during this time that the olfactory bulb begins to grow substantially in volume. Bulb volume increases from the second week into adulthood (greater than 60 d); during the same period, the density of 5-HT remains relatively constant in the infraglomerular layers. Thus, from the second week onward, the growth of 5-HT fibers appears to be closely linked to the increasing volumes of these layers. The density of 5-HT fibers in the glomerular layer, however, continues to increase from the second postnatal week. Thus, the density of fibers in the glomerular layer increases more than the increase in glomerular size, indicating that the glomerular 5-HT fibers are proliferating more than could be accounted for by simple glomerular expansion. In the adult, 5-HT fibers are 2-3 times denser in the glomerular than the infraglomerular layers (McLean and Shipley, 1987). This preferential innervation of glomeruli may be the result of a protracted period of arborization by glomerular versus infraglomerular fibers. This could be due to the prolonged focal release of a trophic factor by glomerular-associated neurons or to the earlier production of an inhibitory factor by infraglomerular neurons.

Pathway formation and the terminal distribution pattern of the spinocerebellar projection in the chick embryo

Pathway formation and the terminal distribution pattern of spinocerebellar fibers in the chick embryo were examined by means of an anterograde labelling technique with wheat germ agglutinin conjugated horseradish peroxidase (WGA-HRP). Spinocerebellar fibers, which originate in the lumbar spinal cord and are located in the marginal layer of the spinal cord, reach the dorsal part of the cerebellar plate on embryonic day (E)8. On the way to the cerebellum the fibers form one distinct bundle, that suggests that gross projection errors probably do not occur during the formation of the spinocerebellar pathway. On E10, labelled fibers are located mostly in the medullary zone of the anterior lobe. By E12, the number of labelled fibers increases greatly in the inner granular and molecular layers. In transverse sections labelling was distributed throughout the mediolateral extent of the medullary zone. By E14, sagittal strips of labelling were clearly recognized in lobules II-IV; however, labelled terminals were present throughout lobule I. Although the adult pattern of terminal distribution is attained by E14, the mossy fiber terminals are still quite immature. The density of labelling decreased greatly by E16, and small terminal varicosities were first recognized. Structural differentiation of mossy fiber terminals continues to the end of the embryonic or the newly posthatched period.

Type V Collagen in Splenic Reticular Fibers of the Macaque Monkey

The distribution of type I, III and V collagens in the monkey spleen was examined by indirect immunofluorescent microscopy and immunoelectron microscopy, and compared with that of reticular fibers revealed by a silver impregnation method. Type I collagen was localized on reticular fibers in the white pulps and on coarse reticular fibers in the splenic cords. Type III collagen was localized on the reticular fibers in the white pulps, and on the coarse reticular fibers and a limited number of fine reticular fibers, in the splenic cords. The anti-type V collagen antibody reacted with annular reticular fibers around the splenic sinuses, as well as with the reticular fibers in the white pulps and with the coarse and fine reticular fibers in the splenic cords. Thus, the distribution pattern of fibers that reacted with the anti-type V collagen antibody was very similar to that of the reticular fibers revealed by the silver impregnation method. Electron-microscopically, the fine reticular fibers in the splenic cords were composed of collagen fibrils, 30-50 nm in diameter, and amorphous substances. They were covered by reticular cell processes. By immunoperoxidase labeling with the anti-type V collagen antibody, electron-dense reaction products were found over the collagen fibrils with a banding pattern. These results indicate that type V collagen is an indispensable component of the reticular fibers.

Aminergic Innervation Pattern of the Rodent Pineal Gland: No Apparent Influence of Time of Day

Pineal melatonin synthetic activity shows distinct diurnal characteristics. The circadian regulation of melatonin synthesis is provided by noradrenaline-releasing sympathetic nerves. The pineal noradrenaline content shows a circadian rhythmicity tidally related to the changes in melatonin synthesis rate. To evaluate possible circadian changes of pineal noradrenergic fibre arrangement, the nerve distribution in rat and guinea pig pineal glands was visualized by means of glyoxylic acid-induced histofluorescence. Histochemical findings at 08.00 h and 24.00 h did not exhibit any differences: in both species a dense, mainly perivascularly located network of fluorescent fibres was encountered. As indicated by the simultaneous intraneural presence of green-bluish and yellow fluorophores these fibres most likely contain noradrenaline and serotonin. Obviously circadian melatonin synthesis changes are not paralleled by changes in the distribution pattern of pineal sympathetic nerve fibers. Like other sympathetic innervation-related morphological parameters, histofluorescence does not accurately reflect circadian biochemical changes in the pineal gland.

Immunocytochemical distribution of luteinizing hormone in rat central nervous system.

This paper presents the first detailed localization of luteinizing hormone (LH)-containing cells and fibers in the rat central nervous system. These immunoreactive elements were identified by four LH antisera, two directed against the intact LH molecule and two against LHb. Cell bodies, immunoreactive for LH were found throughout the rostral-caudal extent of the hypothalamic arcuate and ventromedial nuclei, the periarcuate area ventral to the ventromedial nucleus, and the retrochiasmatic area. Immunopositive fibers were traced to numerous structures within the brain including discrete regions of the hypothalamus, septal area, nucleus of the diagonal band, bed nucleus of stria terminalis, amygdala, thalamus, periaqueductal gray, raphe nuclei, brainstem reticular nuclei, locus ceruleus, parabrachial nucleus, dorsal motor nucleus of vagus, and the nucleus of the solitary tract, with a few fibers extending into spinal cord central gray. This pattern of fiber distribution corresponds closely with those described for fibers containing several other anterior pituitary hormones. The extensive projection for LH may provide neuroanatomical substrate mediating reproductive events as it does in the pituitary, or it may serve some modulatory function in brain which is independent of its role in reproduction.

The opioid peptides and their receptors

[Met]Enkephalin-Arg6-Gly7-Leu8 is an endogenous opioid peptide, first isolated from the bovine adrenal medulla. Because this octapeptide is specifically contained in the amino acid sequence of preproenkephalin A but not in other opioid precursors like preproopiomelanocortin or preproenkephalin B, [Met]enkephalin-Arg6-Gly7-Leu8 has been regarded as a specific marker for preproenkephalin A and its derivatives. In this study, we examined the occurrence and origin of [Met]enkephalin-Arg6-Gly7-Leu8-immunoreactive nerves in the guinea-pig and rat lung by immunohistochemical techniques, using a specific antiserum against this peptide. In addition, we investigated the possible co-existence of [Met]enkephalin-Arg6-Gly7-Leu8 and vasoactive intestinal peptide immunoreactivity in neuronal elements of the respiratory tract. In both species, [Met]enkephalin-Arg6-Gly7-Leu8 immunoreactivity was localized in nerve fibers chiefly distributed to the trachea and major bronchi, where they were prevalent in smooth muscle bundles, in the lamina propria, around airway glands, and in the walls of pulmonary vessels, but were absent in airway epithelium. Slight differences in the distribution pattern of immunoreactive nerve fibers were noted between the two species: immunoreactive nerve fibers in the smooth muscle bundles were much more abundant in guinea-pigs than in rats, while those in the mucous glands were richer in rats than in guinea-pigs. Neither chemical sympathectomy by 6-hydroxydopamine, nor chemical sensory denervation by capsaicin, changed the density or distribution of [Met]enkephalin-Arg6-Gly7-Leu8-immunoreactive nerve fibers in the airway, suggesting an intrinsic source for these nerve fibers. Colchicine injection into the tracheal wall, to promote the accumulation of neuropeptides in nerve cell bodies, led to the visualization of [Met]enkephalin-Arg6-Gly7-Leu8 immunoreactivity in some neuronal cell bodies within airway ganglia. Immunostaining for [Met]enkephalin-Arg6-Gly7-Leu8 and for vasoactive intestinal polypeptide on serial adjacent sections of airway ganglia obtained from colchicine-treated tracheae, demonstrated the co-existence of these immunoreactivities in a population of nerve cell bodies in these ganglia.The immunohistochemical localization of immunoreactive [Met]enkephalin-Arg6-Gly7-Leu8 in nerve elements in guinea-pig and rat lungs provides a morphological basis for the possibility that pre-proenkephalin A-related opioid peptides may have a neuromodulatory role in mammalian airways and pulmonary vessels.

Projections of hindlimb dorsal roots to lumbosacral spinal cord of cat.

Single dorsal roots of spinal nerves that contribute to the cat lumbosacral plexus (L3-S2) were cut to evoke degeneration of centrally projecting axons. Serial sections throughout lumbosacral cord levels were impregnated by the Fink-Heimer method (20) to permit charting of the distribution patterns of segmental dorsal root afferent fibers. Afferent fibers that enter a single dorsal root have an extensive distribution to multiple cord segments; their longitudinal extent varies with entry level and with laminar targets. Afferent projections to the ventral horn reach motor nuclei only in their entry segment and the adjacent segments just above and below their entry. Those afferent fibers projecting to intermediate gray (laminae VI and VII) have the most extensive spinal distribution of any types; they may, from a single dorsal root, reach as many as 13 or 14 cord segments. Dorsal horn projections of single roots are also longitudinally expansive. Small-diameter afferent fibers course rostrally and caudally in Lissauer's tract (LT) for up to 9-10 segments. They appear to terminate in at least laminae I and II in and near their entry segment; their endings are difficult to demonstrate at greater distances where they are probably less dense. Larger caliber axons entering the dorsal horn generate a somatotopically organized projection, especially to laminae III and IV. Collaterals of these fibers appear to course longitudinally within the gray matter and they distribute to as many as six to seven segments.

Characterization of fiber orientation in short-fiber composites

A method for measuring intermediate states of fiber orientation in short-fiber composites is described. The technique is based on the observation that a representative fiber distribution, for example, the negative of a photomicrograph from a specimen, resembles a collection of diffraction apertures. Diffraction masks for a Fraunhofer diffractometer made from the representative fiber distributions produce diffraction patterns characteristic of the state of orientation. Analyses are presented which relate the features of the diffraction pattern to (i) the orientation distribution, (ii) shape, and (iii) aspect ratio of the fibers. The results from these analyses are in good agreement with experimental diffraction patterns from masks made from simulated fiber distribution patterns.