A Golgi study of the hypothalamus of Actinopterygii

Summary The posterior hypothalami of the polypteriform, Calamoichthys, and of the teleost, Anguilla, were studied by means of the Golgi technique. In Calamoichthys, the lateral lobes are not developed and the median lobe is simple. In Anguilla, the median (tuberal) lobe shows lophodendritic, CSF-contacting cells and horizontal cells in the periventricular grey and some reticular elements directed toward the cell-poor lateral areas. In the lateral lobes the periventricular grey is formed by multipolar neurons and a diffuse population of multipolar cells of uncertain identity. The nucleus diffusus lobi lateralis is formed by scarce multipolar neurons, often placed next to the external surface of the brain. The organization of the lateral lobes in Actinopterygii is reminiscent of highly developed integrative regions.Work performed under CNR Project Biology of Reproduction     

The hypothalamus of Lacerta sicula R.

Summary The posterior (caudal) hypothalamus of the lizard, Lacerta sicula R. was investigated by means of Golgi methods. The periventricular grey is formed mainly by isodendritic bipolar and multipolar neurons, while in the lateral hypothalamus a more stellate form of neuronal elements is encountered. CSF-contacting neurons are restricted to the tuberal area and to the paraventricular organ. In the latter area they are highly differentiated and endowed with laterally branched processes. The overall pattern of the lizard hypothalamus (organization of neuropil, lateral nuclei, appearance of cell clusters, morphology of the neuronal elements) represents an intermediate stage in the phylogenetic development of the hypothalamus, being more advanced than the amphibian stage.     

The brain structure of selected trypanorhynch tapeworms

The brain architecture in four species of tapeworms from the order Trypanorhyncha has been studied. In all species, the brain consists of paired anterior and lateral lobes, and an unpaired central lobe. The anterior lobes connect by dorsal and ventral semicircular commissures; the central and lateral lobes connect by a median and an X-shaped crisscross commissure. In the center of the brain, five well-developed compact neuropils are present. The brain occupies a medial position in the scolex pars bothrialis. The ventral excretory vessels are situated outside the lateral lobes of the brain; the dorsal excretory vessels are located inside the brain and dorsal to the median commissure. The brain gives rize four anterior proboscis nerves and four posterior bulbar nerves with myelinated giant axons (GAs). The cell bodies of the GAs are located within the X-commissure and in the bulbar nerves. Highly developed serotonergic neuropils are present in the anterior and lateral lobes; numerous 5-HT neurons are found in the brain lobes including the central unpaired lobe. The X-cross commissure consists of the α-tub-immunoreactive and 5-HT-IR neurites. Eight ultrastructural types of neurons were found in the brain of the three species investigated. In addition, different types of synapses were present in the neuropils. Glial cells ensheath the brain lobes, the neuropils, the GAs, and the bulbar nerves. Glia cell processes form complex branching patterns of thin cytoplasmic sheets sandwiched between adjacent neural processes and filling the space between neurons. Multilayer myelin-like envelopes and a mesaxon-like structure have been found in Trypanorhyncha nervous system. We compared the brain architecture of Trypanorhyncha with that of an early basal cestode taxon, that is, Diphyllobothriidea, and present a hypothesis about the homology of the anterior brain lobes in order Trypanorhyncha; and the lateral lobes and median commissure are homologous brain structures within Eucestoda.     

The structure of the hypothalamic inferior lobes of the blacktip reef shark: Scanning and transmission electron microscopic observations

The inferior lobes of the shark hypothalamus were examined with light, transmission and scanning electron microscopy. The cells bordering the floor of the lateral recess appear to be typical liquor-contacting neurons. With scanning electron microscopy (SEM) the apical ends of these cells are seen to bulge into the ventricular lumen. In contrast, the roof is lined by a more typical ependymal cell characterized by numerous cilia and microvilli. In addition, SEM reveals several kinds of supraependymal cells with processes that appear to penetrate the ventricular lining. A periventricular nucleus underlies the ependymal cells. Neurons of the periventricular nucleus contain numerous lipofuchsin granules. The rest of the inferior lobe consists of many neuronal fibers. The morphology of the hypothalamic inferior lobe is discussed in relation to its possible role in feeding and aggressive behavior in both elasmobranchs and teleosts.     

A Golgi study on the neuronal morphology in the hypothalamus of the Japanese quail (Coturnix coturnix japonica)

Neuronal morphology and dendritic architecture of the tuberal and mammillary regions in the hypothalamus of the quail (Coturnix coturnix japonica) were investigated by means of classical neuroanatomical methods (Bodian silver impregnation, Luxol-fast blue, cresyl violet, toluidine blue, rapid Golgi method). The tuberal region is characterized by isodendritic neurons, in particular: a) pyriform and bipolar neurons, occasionally arranged diagonally to the ventricular surface; b) CSF-contacting neurons, located subependymally or more deeply in the periventricular gray, which are especially abundant in the paraventricular organ and in the proximity of the median eminence; c) numerous multipolar neurons, endowed with stout, almost unbranched dendritic processes, occupying generally the medio-lateral areas of the hypothalamus. Some multipolar neurons display somata, pyramidal or ovoidal in shape, almost imperceptibly tapering into three or more dendritic trunks. These relatively straight and long dendrites are rich in dendritic spines. In the mammillary region, Golgi impregnation shows multipolar neurons of medium size, most likely belonging to the lateral mammillary nucleus.     

The bronchial tree and lobular division of the chimpanzee lung

The bronchial ramification and lobular division in lungs of two chimpanzees (Pan troglodytes) were examined from the viewpoint of comparative anatomy, on the basis of the fundamental structure of bronchial ramification of the mammalian lung (Nakakuki, 1975, 1980). The right lung of the chimpanzee consists of the upper, middle, and lower lobes, whereas the left lung consists of the middle and lower lobes. The right and left lungs have the dorsal bronchiole system, lateral bronchiole system, and medial bronchiole system. The ventral bronchiole system is lacking on both sides. The right upper lobe is formed by the first branch of the dorsal bronchiole system. The right middle lobe is formed by the first branch of the lateral bronchiole system, and the right accessory lobe bronchiole is lacking. The remaining bronchioles constitute the right lower lobe. In the left lung, the upper and accessory lobes are lacking. The well developed middle lobe is formed by the first branch of the lateral bronchiole system. The left lower lobe is formed by the remaining bronchioles. Furthermore, these bronchioles are compared with those of the human lung byBoyden (1955).     

Specializations within the lumbosacral spinal cord of the pigeon

The prominent accessory lobes of Lachi in birds are considered to be marginal nuclei; similar nuclei have been implicated in mechanoreceptive functions in snakes and lampreys. Reptile studies emphasized the involvement of the denticulate ligament with this mechanoreceptive function. This investigation examines the fine structure of the accessory lobes of Lachi in pigeons and their interaction with ligaments for features which might support such a mechanoreceptive function. In the lumbosacral area of the spinal cord, the lateral longitudinal ligaments and the ventral longitudinal ligament are hypertrophied. The ventral transverse ligaments are present only within the lumbosacral segments of the spinal cord and they interconnect with the lateral and ventral longitudinal ligaments. The lateral longitudinal ligament makes intimate contact with the spinal cord, and many glial processes from the spinal cord mingle with and are firmly attached to collagenous fibers of the ligament. The lobes lie dorsal to the lateral longitudinal ligament in the exact area where it interconnects with the transverse ligament. The lobe's multipolar neurons have a number of synaptic contacts but no unusual specializations were noted. Most of each lobe is composed of interdigitating saccular structures filled to varying degrees with flocculent material. The sacs are extensions of the cytoplasm of neuroglial cells, which also give rise to membranes surrounding neuronal processes and the sacs themselves. A possible functional relationship of the lobes and the ligaments of the lumbosacral spinal segments within the vertebral column is described.     

Physiology and morphology of olfactory neurons associating with the protocerebral lobe of the honeybee brain

Physiology and morphology of olfactory neurons associated with the protocerebral lobe around the alpha-lobe of the mushroom body were studied in the brain of the honeybee Apis mellifera using intracellular recording and staining techniques. The responses of neurons to behaviorally relevant odorants (a blend, and components of the Nasonov pheromone, and some other non-pheromonal odors) were recorded. Different response patterns were observed within different neurons, and often within the same neuron, in response to different stimuli. All the neurons stained had innervations in the protocerebral lobe. The cell profiles varied from cells connecting the antennal lobe with both the protocerebral and lateral protocerebral lobes (projection neurons), cells linking the pedunculus of the mushroom body with both the protocerebral and lateral protocerebral lobes (PE1 neurons), cells linking the alpha-lobe and protocerebral lobe with the calyces of the mushroom body (feedback neurons), and cells linking the alpha-lobe and protocerebral lobe with the antennal lobe (recurrent neurons), to cells connecting the protocerebral lobe with the contralateral protocerebrum (bilateral neurons). These findings suggest that the protocerebral lobe acts as an olfactory center associating with other centers, and provides multi-layered recurrent networks within the protocerebrum and between the deutocerebrum and the protocerebrum in honeybee olfactory pathways.     

Neuronal and synaptic organization in the gravity receptor system of the statocyst of Octopus vulgaris

Summary The optic tectum of Calamoichthys calabaricus (Polypteriformes) shows a relatively complex vertical stratification, with six main layers and a varied neuronal typology. In particular, pyriform neurons in the well developed stratum griseum periventriculare and some multipolar neurons in the stratum griseum profundum represent the efferent elements of the tectum, while the optic and lemniscal inputs to the tectum converge in the plexiform sublayers of the stratum fibrosum et griseum superficiale. In the circuitry of the tectum some modulation is achieved by some of the polymorphic cells of the stratum griseum internum and by the horizontal cells of the outer layers. Notwithstanding some differences with respect to the teleost optic lobe (i.e., the absence of a torus longitudinalis; the lack of a stratum fibrosum marginale; the modest size of the stratum fibrosum profundum; the paucity of neurons in the stratum fibrosum et griseum superficiale; and the ill-defined separation of the layers of the afferent and efferent fibers), the optic tectum of Calamoichthys resembles the mesotectal type characteristic of teleosts, anurans and reptiles. It exhibits higher degree of organization than the optic tectum of the Chondrostei.     

Crustacean cardioactive peptide-immunoreactive neurons innervating brain neuropils,retrocerebral complex and stomatogastric nervous system of the locust,Locusta migratoria

The distribution and morphology of crustacean cardioactive peptide-immunoreactive neurons in the brain of the locust Locusta migratoria has been determined. Of more than 500 immunoreactive neurons in total, about 380 are interneurons in the optic lobes. These neurons invade several layers of the medulla and distal parts of the lobula. In addition, a small group of neurons projects into the accessory medulla, the lamina, and to several areas in the median protocerebrum. In the midbrain, 12 groups or individual neurons have been reconstructed. Four groups innervate areas of the superior lateral and ventral lateral protocerebrum and the lateral horn. Two cell groups have bilateral arborizations anterior and posterior to the central body or in the superior median protocerebrum. Ramifications in subunits of the central body and in the lateral and the median accessory lobes arise from four additional cell groups. Two local interneurons innervate the antennal lobe. A tritocerebral cell projects contralaterally into the frontal ganglion and appears to give rise to fibers in the recurrent nerve, and in the hypocerebral and ingluvial ganglia. Varicose fibers in the nervi corporis cardiaci III and the corpora cardiaca, and terminals on pharyngeal dilator muscles arise from two subesophageal neurons. Some of the locust neurons closely resemble immunopositive neurons in a beetle and a moth. Our results suggest that the peptide may be (1) a modulatory substance produced by many brain interneurons, and (2) a neurohormone released from subesophageal neurosecretory cells.     

Golgi study of the anterior dorsal ventricular ridge in a lizard. I. neuronal typology in the adult

Using Golgi techniques we have studied neuronal cell types in the anterior dorsal ventricular ridge (ADVR) of the adult lizard Gallotia galloti. Multipolar, bitufted, and juxtaependymal neuronal forms were found. The multipolar and bitufted neurons are present in both the periventricular and central ADVR zones. Multipolar neurons can be subdivided into multipolar neurons with polygonal somata and four to six main dendritic trunks and multipolar neurons with pyramidal somata and three or more dendritic trunks. The former are the cells most frequently impregnated in the ADVR. In the population of bitufted neurons, we distinguish subtypes I, II, and III according to the number of dendritic trunks that emerge from the somata. Juxtaependymal neurons are restricted to a cell-poor zone, adjacent to ependymal cells. Their dendrites either are orientated parallel to the ventricular surface or extend into the periventricular zone. The dendrites of ADVR neurons have pedunculated spines with knob-like tips. However, such spines do not appear on the somata or on the primary dendritic trunks. The number of spines is scarce or moderate. The periventricular neuronal clusters contain two to five cells. The morphology of these neurons is mainly multipolar, but we also found some bitufted neurons.     

The hypothalamus of Lacerta sicula R.

Summary An analysis of the preoptic area of the lizard, Lacerta sicula R., with the use of the Golgi method revealed that: 1)in principle, the dendritic pattern of its neurons is relatively simple; 2) the supraoptic nucleus contains large- to medium-sized bipolar or multipolar neurons together with small, usually multipolar nerve cells; 3) the preoptic periventricular gray and the paraventricular nucleus exhibit a varied neuronal typology, including large multipolar or bipolar elements, abundant CSF-contacting neurons, and some tufted elements; and 4) the lateral regions display some conspicuous multipolar neurons.With a financial contribution from Ministero della Pubblica Istruzione     

The lobular division,bronchial tree and blood vessels of the squirrel monkey lung

The lobular division, bronchial tree, and blood vessels in lungs of seven squirrel monkeys (Saimiri sciureus) were examined from the viewpoint of comparative anatomy. The right lung of the squirrel monkey consists of the upper, middle, lower, and accessory lobes, whereas the left lung consists of the upper, middle, and lower lobes. These lobes are completely separated by interlobular fissures. In three of seven examples examined the left middle lobe was lacking. The squirrel monkey lung has four bronchiole systems, i.e. dorsal, lateral, ventral, and medial, on both sides. The upper lobes are formed by the first branches of the dorsal bronchiole systems. The middle lobes are formed by the first branches of the lateral bronchiole systems. The remaining bronchioles constitute the lower lobes. In addition to the above lobes, in the right lung, the accessory lobe is present, being formed by the first branch of the ventral bronchiole system. The right pulmonary artery runs across the ventral side of the right upper lobe bronchiole, and then across the dorsal side of the right middle lobe bronchiole. Thereafter, it runs between the dorsal bronchiole and lateral bronchiole systems along the dorso-lateral side of the right bronchus. During its course, the right pulmonary artery gives off the arterial branches which run along each bronchiole. These branches run mainly along the dorsal or lateral side of the bronchioles. In the left lung, the pulmonary artery and its branches run the same course as in the right lung. The pulmonary veins run mainly the ventral or medial side of the bronchioles, and between the bronchioles.     

Anatomy of antenno-cerebral pathways in the brain of the sphinx moth Manduca sexta

Summary In the moth Manduca sexta, the number and morphology of neuronal connections between the antennal lobes and the protocerebrum were examined. Cobalt injections revealed eight morphological types of neurons with somata adjacent to the AL neuropil that project in the inner, middle, and outer antenno-cerebral tracts to the protocerebrum. Neurons innervating the macroglomerular complex and many neurons with fibers in the inner antennocerebral tract have uniglomerular antennal-lobe arborizations. Most neurons in the middle and outer antenno-cerebral tracts, on the other hand, seem to innervate more than one glomerulus. Protocerebral areas receiving direct input from the antennal lobe include the calyces of the mushroom bodies, and circumscribed areas termed olfactory foci in the lateral horn of the protocerebrum and several other regions, especially areas in close proximity to the mushroom bodies. Fibers in the inner antenno-cerebral tract that innervate the male-specific macroglomerular complex have arborizations in the protocerebrum that are distinct from the projections of sexually non-specific neurons. Protocerebral neurons projecting into the antennal lobe are much less numerous than antennal-lobe output cells. Most of these protocerebral fibers enter the antennal lobe in small fiber tracts that are different from those described above. In the protocerebrum, these centrifugal cells arborize in olfactory foci and also in the inferior median protocerebrum and the lateral accessory lobes. The morphological diversity of connections between the antennal lobes and the protocerebrum, described here for the first time on a single-cell level, suggests a much greater physiological complexity of the olfactory system than has been assumed so far.     

The bronchial tree and lobular division of the gorilla lung

The bronchial ramification in one specimen of gorilla lung was examined from the viewpoint of comparative anatomy, on the basis of the fundamental structure of bronchial ramification in the mammalian lung (Nakakuki, 1975, 1980). The right lung of the gorilla consists of the upper, middle, lower, and accessory lobes. The right lung has the dorsal, lateral, and ventral bronchiole systems, but the medial bronchiole system is lacking. The upper lobe is formed by the first branch of the dorsal bronchiole system. The middle lobe is formed by the first branch of the lateral bronchiole system. The accessory lobe is formed by the first branch of the ventral bronchiole system. The remaining bronchioles constitute the lower lobe. The left lung consists of the middle and lower lobes; the upper and accessory lobes are lacking. The left lung has the dorsal and lateral bronchiole systems, but the ventral and medial bronchiole systems are lacking. The middle lobe is formed by the first branch of the lateral bronchiole system. The remaining bronchioles constitute the lower lobe. The bronchial ramifications of the gorilla lung are rather similar to those of the human lung.     

The bronchial tree,lobular division,and blood vessels of the lung of the Diana monkey (Cercopithecus diana)

The authors examined the lung of one Diana monkey (Cercopithecus diana). The right lung consists of upper, middle, lower, and accessory lobes, the upper and middle lobes being united dorsally. The accessory and lower lobes are separated from the other lobes by fissures. The left lung consists of a bi-lobed middle lobe and a lower lobe. These lobes are separated by an interlobular fissure. The Diana monkey has dorsal, lateral, ventral, and medial bronchiole systems on either side. The upper lobe is formed by the first bronchiole of the dorsal bronchiole system. The middle lobe is formed by the first bronchiole of the lateral bronchiole system and the accessory lobe is formed by the first bronchiole of the ventral bronchiole system. The remaining bronchioles of the four bronchiole systems constitute the lower lobe. The right pulmonary artery runs across the ventral side of the right upper lobe bronchiole, and then across the dorsal side of the right middle lobe bronchiole. Thereafter, it runs between the dorsal and lateral bronchiole systems, along the dorso-lateral side of the right bronchus. During its course, the right pulmonary artery gives off arterial branches running along the dorsal or lateral side of each bronchiole. The left pulmonary artery runs across the dorsal side of the left middle lobe bronchiole. Thereafter, it follows the same course as in the right lung, giving off arterial branches. The pulmonary veins run along the ventral or medial side of the bronchiole, and between the bronchioles.     

The bronchial tree and lobular division of the lung of the white handed gibbon

The bronchial tree and lobular division of the lungs of four white handed gibbons (Hylobates agilis) were examined from the viewpoint of comparative anatomy, based upon the fundamental structure of the bronchial ramifications of the mammalian lung (Nakakuki, 1975, 1980). The right lung of the white handed gibbon consists of the upper, middle, lower, and accessory lobes, whereas the left lung consists of the middle and lower lobes. Each lobe is separated by the interlobular fissure, on both sides. The right and left lungs have the dorsal bronchiole system, lateral bronchiole system, and ventral bronchiole system. The medial bronchiole system is lacking on both sides. In the right lung, the upper lobe is formed by the first branch of the dorsal bronchiole system. The middle lobe is formed by the first brach of the lateral bronchiole system, and the accessory lobe by the first branch of the ventral bronchiole system. The remaining bronchioles constitute the right lower lobe. In the left lung, the upper lobe bronchiole, which is the first branch of the dorsal bronchiole system, is lacking. Therefore, the middle lobe bronchiole, i.e. the first branch of the lateral bronchiole system, is well developed. The accessory lobe bronchiole, the first branch of the ventral bronchiole system, is also lacking. The remaining bronchioles constitute the left lower lobe. These features were compared with those of other apes and man.     

A golgi study on tanycytes and liquor-contacting cells in the posterior hypothalamus of the newt

Summary Golgi methods were employed to study neurons and ependymal tanycytes in the posterior hypothalamus of the newt. The tanycytes send a few coarse, spiny or barbed processes towards the pia mater. In the periventricular grey, the neurohistological methods show common neurons, ranging from a multipolar to a plumed organization, and abundant liquor-contacting cells. These cells, possibly neurons, give rise to a process that reaches the cerebro-spinal fluid, and terminates in a spindle-shaped swelling, with a thin thread at its tip. In other cells, the intraventricular endings are bulbous or finger-like. The occurrence of: (1) branches of the liquor-contacting process, running parallel to the infundibular surface; (2) infundibular processes which end at the base or between the ependymal cell bodies; and (3) axons coursing in the same position, all indicates that the subependymal layer is a site for complex intercellular relationships. The significance of liquor-contacting cells and tanycytes is discussed, in view of the possibility that they may represent part of a system for hypothalamic regulation in response to changes in the CSF.     

Immunohistochemical localization of delta sleep-inducing peptide (DSIP) in the brain and pituitary of the cartilaginous fish Scyliorhinus canicula.

The distribution of delta sleep-inducing peptide (DSIP) in the brain and pituitary of the cartilaginous fish Scyliorhinus canicula was investigated using the indirect immunofluorescence technique. Delta sleep-inducing peptide-like immunoreactive cell bodies were mainly observed in the nucleus lateralis tuberis of the hypothalamus. Immunolabeled perikarya were also distributed in the nucleus lobi lateralis hypothalami and in the dorso-lateral wall of the recessus posterioris. Most of these cells, located in the subependymal layers of the infundibulum and lateral lobes, had the typical aspect of cerebrospinal fluid-contacting elements. The DSIP-like immunoreactive fibers were localized in the basal telencephalon, within the regions of the nucleus interstitialis commissurae anterioris and the nucleus entopeduncularis. A dense network of DSIP-positive fibers was seen throughout the midcaudal hypothalamus, the lateral lobes, and the posterior lobe. In the pituitary, numerous DSIP-like immunoreactive cells were detected in the median lobe of the pars distalis. In particular, a high concentration of cells was seen in the dorsal wall of the median lobe, an area which is known to contain melanin-concentrating hormone (MCH)-producing cells. Comparison of the distribution of DSIP- and MCH-like immunoreactive cells revealed that the two neuropeptides are stored in the same cells of the median lobe of the pituitary. These findings provide the first evidence for the presence of a DSIP-related peptide in fish. The distribution of the immunoreactive material supports the view that DSIP may act as a neuromodulator and/or a hypophysiotropic factor. Moreover, the presence of DSIP-like immunoreactive cells in the pars distalis suggests that this peptide may exert autocrine or paracrine effect in the pituitary.     

NO/cGMP signalling: <Emphasis Type="SmallCaps">L</Emphasis>-citrulline and cGMP immunostaining in the central complex of the desert locust <Emphasis Type="Italic">Schistocerca gregaria</Emphasis>

Nitric oxide (NO) is a gaseous messenger molecule formed during conversion of L-arginine into L-citrulline by the enzyme NO synthase (NOS), which belongs to a group of NADPH diaphorases. Because of its gaseous diffusion properties, NO differs from classical neurotransmitters in that it is not restricted to synaptic terminals. In target cells, NO activates soluble guanylyl cyclase leading to an increase in cGMP levels. In insects, this NO/cGMP-signalling pathway is involved in development, memory formation and processing of visual, olfactory and mechanosensory information. We have analysed the distribution of putative NO donor and target cells in the central complex, a brain area involved in sky-compass orientation, of the locust Schistocerca gregaria by immunostaining for L-citrulline and cGMP. Six types of citrulline-immunostained neurons have been identified including a bilateral pair of hitherto undescribed neurons that connect the lateral accessory lobes with areas anterior to the medial lobes of the mushroom bodies. Three-dimensional reconstructions have revealed the connectivity pattern of a set of 18 immunostained pontine neurons of the central body. All these neurons appear to be a subset of previously mapped NADPH-diaphorase-positive neurons of the central complex. At least three types of central-complex neurons show cGMP immunostaining including a system of novel columnar neurons connecting the upper division of the central body and the lateral triangle of the lateral accessory lobe. Our results provide the morphological basis for further studies of the function of the labelled neurons and new insights into NO/cGMP signalling. This work was supported by DFG grant HO 950/16-2.