Effect of whole-body gamma irradiation on the ultrastructure of the respiratory cells of the lungs

Edema developed in the respiratory and endothelial cells cytoplasm after whole-body gamma-irradiation. In the cytoplasm of granular cells, the osmiophilic substance level decreased and giant laminar bodies periodically formed reducing the respiratory and endothelial cells edema. Collagen fibres actively grew in the interstice and capillary lumens.     

Structure of newly formed capillaries of the rabbit cornea (electron microscopic study)

Owing to a complex application of topical analysis and tracer technique, it is possible to carry out a light optic and electron microscopic investigation of newly formed capillaries growing in the rabbit cornea after its chemical burn. The ultrastructural analysis demonstrates certain polymorphism of morphological organization of endotheliocyte in the newly formed capillaries. There is a rather elevated amount of free ribosomes, mitochondria, microtubules and microfilaments in cytoplasm. The granular endoplasmic reticulum and Golgi complex are hypertrophied. Weibel--Palade bodies appear. Taking into account certain morpho-functional peculiarities of endothelial cells along the course of the growing capillaries, on the 8th day of growth three zone are distinguished: 1--area of nondifferentiated endothelium (apex of the capillary), 2--transitional zone, 3--zone of relatively differentiated endothelium situating in the place where the capillary gets off the parental vessel. According to the zones distinguished, the ways of trans-endothelial transport of molecules are investigated. In formation of the capillary barrier-transport function an important role belongs to polymorphism of the endothelial cells along the course of the growing capillary which is determined by differentiation degree of these cells depending on their participation in permeability.     

Growth cones stall and collapse during axon outgrowth in Caenorhabditis elegans.

During nervous system development, neurons form synaptic contacts with distant target cells. These connections are formed by the extension of axonal processes along predetermined pathways. Axon outgrowth is directed by growth cones located at the tips of these neuronal processes. Although the behavior of growth cones has been well-characterized in vitro, it is difficult to observe growth cones in vivo. We have observed motor neuron growth cones migrating in living Caenorhabditis elegans larvae using time-lapse confocal microscopy. Specifically, we observed the VD motor neurons extend axons from the ventral to dorsal nerve cord during the L2 stage. The growth cones of these neurons are round and migrate rapidly across the epidermis if they are unobstructed. When they contact axons of the lateral nerve fascicles, growth cones stall and spread out along the fascicle to form anvil-shaped structures. After pausing for a few minutes, they extend lamellipodia beyond the fascicle and resume migration toward the dorsal nerve cord. Growth cones stall again when they contact the body wall muscles. These muscles are tightly attached to the epidermis by narrowly spaced circumferential attachment structures. Stalled growth cones extend fingers dorsally between these hypodermal attachment structures. When a single finger has projected through the body wall muscle quadrant, the growth cone located on the ventral side of the muscle collapses and a new growth cone forms at the dorsal tip of the predominating finger. Thus, we observe that complete growth cone collapse occurs in vivo and not just in culture assays. In contrast to studies indicating that collapse occurs upon contact with repulsive substrata, collapse of the VD growth cones may result from an intrinsic signal that serves to maintain growth cone primacy and conserve cellular material.     

A neural network model for limb trajectory formation

This paper deals with the problem of representing and generating unconstrained aiming movements of a limb by means of a neural network architecture. The network produced time trajectories of a limb from a starting posture toward targets specified by sensory stimuli. Thus the network performed a sensory-motor transformation. The experimenters trained the network using a bell-shaped velocity profile on the trajectories. This type of profile is characteristic of most movements performed by biological systems. We investigated the generalization capabilities of the network as well as its internal organization. Experiments performed during learning and on the trained network showed that: (i) the task could be learned by a three-layer sequential network; (ii) the network successfully generalized in trajectory space and adjusted the velocity profiles properly; (iii) the same task could not be learned by a linear network; (iv) after learning, the internal connections became organized into inhibitory and excitatory zones and encoded the main features of the training set; (v) the model was robust to noise on the input signals; (vi) the network exhibited attractor-dynamics properties; (vii) the network was able to solve the motorequivalence problem. A key feature of this work is the fact that the neural network was coupled to a mechanical model of a limb in which muscles are represented as springs. With this representation the model solved the problem of motor redundancy.     

Innervation zones of the upper and lower limb muscles estimated by using multichannel surface EMG

The distribution of innervation zones was investigated in 3 subjects for 17 muscles and 8 muscle groups in the upper and lower limb, by detecting bi-directional propagation of motor unit action potentials (MUAPs) with the multichannel surface electrode array. Clarification of the distribution of innervation zones depended on the ease in detecting the propagation of MUAPs and the actual scattering of innervation zones, which were closely related with muscle morphology with respect to the arrangements of muscle fibers. In muscles having fibers running parallel to each other, such as the biceps brachii, intrinsic hand muscles, vastus lateralis and medialis, tensor fasciae latae, peronei, soleus, tibialis anterior, and hypothenar muscles in the foot, it was relatively easy to detect the propagating MUAPs, and the innervation zones were distributed in a relatively narrow band around muscle belly. On the other hand, in muscles with a complicated structure including pinnation of muscle fibers, in-series muscle fibers and aponeurotic tissues, such as the deltoid, flexors and extensors in the forearm, rectus femoris, sartorius, hamstrings and gastrocnemius, it was more difficult to detect the propagating MUAPs and to identify the innervation zones, which were widely scattered or distributed in complex configurations. The distribution of the innervation zones clarified in the present study can be used to find the optimal location of electrodes in surface EMG recordings and of stimulus electrodes in the functional and therapeutic electrical stimulations. It may also be useful in motor point biopsy for diagnosis of neuromuscular diseases as well as in the botulinum toxin injection for the treatment of spasticity.     

Attraction vs. repulsion: the growth cone decides.

Axons are guided through their environment in response to signals provided by extracellular cues. These cues are transduced into motile responses by the tip of the growing axon, the growth cone, and can be either repulsive or attractive in nature. Recent studies have suggested that how an axon responds to any given signal depends on the internal state of the growth cone. This review discusses these studies and their importance for understanding how nerve connections are made in the developing embryo.     

Observation of Potato Virus X in Tobacco Mosaic Virus (TMV)- Induced Local Lesions and Surrounding Zones in Leaves of Datura stramonium L. in Mixed Infection

In mixed infection by Tobacco Mosaic Virus (TMV) and Potato Virus X (PVX) of leaves of Datura stramonium L., PVX particles were observed in the developing local lesions in both the central part and on the periphery, in addition to TMV. PVX virions were found either separately or together with TMV. Sometimes in local lesions mainly in their periphery, PVX-specific laminar inclusion components were observed and, in certain cases, cylindrical bodies about 120—140 nm in diameter. In 2 mm surrounding zones from the edge of the lesions, TMV particles were not observed. However, in the majority of cells of these zones, PVX intensively accumulated, often forming large masses. In some cases, we observed parts of cells with relatively small amounts of dispersed PVX particles, associated with laminar inclusion bodies. In cell areas with large accumulations of PVX, laminar inclusions were not found.     

Neurocalcin-like immunoreactivity in the rat esophageal nervous system

Neurocalcin is a newly identified neuronal calcium-binding protein. We tried here to investigate the immunohistochemical distribution of neurocalcin in the rat esophagus. Nerve cell bodies having neurocalcin immunoreactivity were found throughout the myenteric plexus. In the myenteric ganglia, two types of nerve terminals showed neurocalcin immunoreactivity. One was varicose terminals containing numerous small clear vesicles and forming a synapse with nerve cells. The other terminals were characterized by laminar or pleomorphic structure and many mitochondria. These laminar terminals were supposed to be sensory receptors of the esophageal wall. In the motor endplates of the striated muscles, nerve terminals containing many small clear vesicles and mitochondria also had neurocalcin immunoreactivity. After left vagus nerve cutting under the nodose ganglia, the number of immunopositive thick nerve fibers, laminar endings and nerve terminals on the striated muscles decreased markedly. Retrograde tracing experiments using Fast Blue showed extrinsic innervation of esophagus from ambiguus nucleus, dorsal motor nucleus of vagus, superior cervical ganglia, celiac ganglia, nodose ganglia and dorsal root ganglia. In the celiac ganglia, nodose ganglia and dorsal root ganglia, retrogradely labeled nerve cells were neurocalcin-immunoreactive. Neurons in the celiac ganglia may project varicose terminals, while nodose and dorsal root neurons project laminar terminals. Although cell bodies of motoneurons in the ambiguus nucleus lacked neurocalcin immunoreactivity, these neurons may contain neurocalcin only in the nerve terminals in the motor endplates. Neurocalcin immunoreactivity is distributed in many extrinsic and intrinsic neurons in the esophagus and this protein may play important roles in regulating calcium signaling in the neurons.     

An unsupervised neural network model for the development of reflex co-ordination

In this paper, we present a model for the development of connections between muscle afferents and motoneurones in the human spinal cord. The model consists of a limb with six muscles, one motoneurone pool, one pooled (Ia-like) afferent for each muscle and a central programme generator. The weights of the connections between the afferents and the motoneurone pools are adapted during centrally induced movements of the limb. The connections between the afferents and the motoneurone pools adapt in a hebbian way, using only local information present at the synapses. This neural network is tested in two examples of a limb with two degrees of freedom and six muscles. Despite the simplifications, the model predicts the pattern of autogenic and heterogenic monosynaptic reflexes quite realistically.     

Ultrastructural characteristics of the capillary basement membrane of the cerebral cortex in normal state and in severe focal diseases]

The capillary basal membranes of the cerebral cortex in adult rats and man have similarultrastructure in normality. The same formation of capillaries of the cerebral cortex of 1 day old rats is characterized by a not uniform structure and relatively low electron-optical density. The capillary basal membrane of the cortex of patients not older than 30 with severe focal lesions of the brain has increased thickness in some portions where it iscomposed of a homogenous substance, osmophilic granules, light cavities of different size and shape, vesicles restricted with a sheath and rare dense bodies. In elderly patients older that 40 the capillary basal membrane in thicker zones appears to be more electron dense and homogeneous than in younger patients.     

Ultrastructure of the subepidermal musculature of Xenoturbella bocki, the adelphotaxon of the Bilateria

 Xenoturbella bocki is the only species of the high-ranked taxon Xenoturbellida. The species lives on marine mud bottoms at a depth of 20–120 m and moves extremely slowly by ciliary gliding. Nevertheless it possesses a well-developed body wall musculature with outer circular muscles, a prominent layer of inner longitudinal muscles and radial muscles that extend from the outer circular myocytes to the musculature surrounding the gastrodermis. The longitudinal myocytes are not compact cells, but form fascicles of fibrils running parallel to each other. Fine cytoplasmic cords connect the fibres of a cell to each other and with its nuclear region. The muscles are embedded within a sometimes expansive extracellular matrix (ECM) that lacks any fibrillar components. All muscle cells display conspicuous and numerous cytoplasmic extensions that are intermingled with each other. Tight coupling between adjacent cell membranes is not found, but zonula adhaerens-like junctions exist. Fibrils belonging to different myocytes, but also fibrils of the same cell, are coupled by such cytoplasmic extensions. Circular, radial and at least the peripheral longitudinal myocytes display cell-matrix connections with the internal lamina, a component of the subepidermal ECM. This internal lamina projects down into the centres of the fascicles with longitudinal muscle fibrils and forms extensive attachment zones with the muscle cells, reminiscent of focal contacts. For the ingestion of food, X. bocki opens the simple mouth pore and protrudes the aciliated gastrodermis. The body wall musculature is responsible for this protrusion and also for the withdrawal of the gastrodermis. In the past, possible phylogenetic kinships with the Acoelomorpha (Plathelminthes) or the Enteropneusta and Holothuroidea were discussed, but, on the basis of all information available, X. bocki is hypothesized to be the sister taxon of the Bilateria. Accepted: 2 April 1997     

A morphological study of the vertebral venous plexus and its connections in the Cape dune mole‐rat,Bathyergus suillus (Bathyergidae)

Bathyergus suillus are subterranean rodents found in the Western Cape of South Africa, where they inhabit sandy, humid burrows. Vertebral venous plexuses around the vertebral column have been implicated in aiding the maintenance of a constant central nervous system temperature via its connections with muscles and interscapular brown adipose tissue. The morphology of the vertebral venous plexuses and its connections in B.suillus were investigated. Frozen (n = 10) animals were defrosted; the venous system injected with latex and the vertebral venous plexuses, azygos‐ and intercostal veins dissected along the dorsal and ventral aspects of the vertebral column. Specimens (n = 4) were used for histological serial cross sections of the thoracic vertebrae. Veins drained from the interscapular brown adipose tissue to the external vertebral venous plexus, via a dorsal vein at the spinous process of T2 which might represent the “vein of Sulzer” described in rats. The intercostal veins cranial to the level of T8 drained directly into the ventral external vertebral venous plexus instead of into the azygos vein as seen in rats. The azygos vein was situated ventrally on the thoracic vertebral bodies in the median plane as opposed to most rodents that have a left sided azygos vein. The internal vertebral venous plexus consisted of two ventrolateraly placed longitudinal veins in the spinal epidural space. Veins from the forelimbs entered the internal vertebral venous plexus directly at the levels of C7 and T1 and have not been described in other rodents. Serial histological sections, revealed no regulatory valves in vessels leading toward the internal vertebral venous plexus, allowing blood to presumably move in both directions within the vertebral venous plexus. The vertebral venous plexus of B. suillus shows similarities to that of the rat but the vessels from the forelimbs draining directly into to the internal vertebral venous plexus and the position of the azygos vein and the intercostal veins draining into the external vertebral venous plexus are notable exceptions. J. Morphol., 2011. © 2010 Wiley‐Liss, Inc.     

The reticular substance of the medulla oblongata of the albino rat

Summary The region of the reticular giganto-cellular nucleus, perfused with formalin and postfixed in osmium tetroxide, was studied with histochemical and electron microscopic techniques. The perikarya of the neurons have two zones. The peripheral cytoplasm contains Nissl bodies, mitochondria, and free RNP particles. The juxtanuclear cytoplasm contains the Golgi complex, mitochondria, RNP particles and dense bodies. The nucleus is indented and has a prominent nucleolus and a paranucleolar body. Dense bodies are found along the axon and dendrites as well. Three different types of synapses are described and two types of synaptic vesicles (spherical and ellipsoidal) are shown.The capillary endothelium shows microvilli and marginal flaps. The endothelial cytoplasm contains vacuoles, micropinocytotic vesicles, and a few dense bodies. Processes of pericapillary cells, surrounded by a basement membrane, also contain dense bodies. The dense bodies found in the neurons and endothelial cells show acid phosphatase activity. On the basis of their morphology and their enzymatic activity these bodies are identified as lysosomes.Partially supported by a school grant No RF 62051 from the Rockefeller Foundation, New York, USA, and Consejo Nacional de Investigaciones Científicas y Técnicas, Argentina.Fellows of the Consejo National de Investigaciones Científicas y Técnicas, Argentina. The authors wish to thank Dr. Mario H. Burgos for his constant interest and criticism, and to Dr. Eduardo Rodriguez Echandia and Dr. Fabio L. Sacerdote for their valuable assistance.     

Morphological and histochemical characterization of the pectoral fin muscle of the stripped weakfish,Cynoscion guatucupa

The fibres of superficial and deep abductor muscles of the pectoral fins of the stripped weakfish, Cynoscion guatucupa have been studied using histochemical techniques: succinic dehydrogenase (SDH) for mitochondria, periodic acid–Schiff (PAS) for glycogen, myosin‐adenosintriphosphatase (mATPase) to identify different fibre types based on the contraction speed and modified ATPase to identify capillaries. The fibre diameters were measured, and the capillaries of the main fibre types – red, pink and white— were counted. The two muscles showed both macroscopically and microscopically two well‐differentiated zones with predominant white fibres. The area of insertion of muscles into the fin rays had red, pink and white fibres. The origin zone of the muscle into the bone was composed by white fibres only. Both zones of white muscle evidenced a mosaic of small, medium and large polygonal white fibres. Red, pink and white muscles showed a wide histochemical diversity of fibre subtypes. The area per peripheral capillary increased from the red to the white muscles. Due to the predominance of white fibres, the pectoral fins of C. guatucupa were mainly involved in rapid movements to stop/discontinue and stabilize the body during swimming.     

Passive mechanics of canine internal abdominal muscles.

The internal abdominal muscles are biaxially loaded in vivo, and therefore length-tension relations along and transverse to the directions of the muscle fibers are important in understanding their mechanical properties. We hypothesized that 1) internal oblique and transversus abdominis form an internal abdominal composite muscle with altered compliance than that of either muscle individually, and 2) anisotropy, different compliances in orthogonal directions, of internal abdominal composite muscle is less pronounced than that of its individual muscles. To test these hypotheses, in vitro mechanical testing was performed on 5 x 5 cm squares of transversus abdominis, internal oblique, and the two muscles together as a composite. These tissues were harvested from the left lateral side of abdominal muscles of eleven mongrel dogs (15-23 kg) and placed in a bath of oxygenated Krebs solution. Each tissue strip was attached to a biaxial mechanical testing device. Each muscle was passively lengthened and shortened along muscle fibers, transverse to fibers, or simultaneously along and transverse to muscle fibers. Both transversus abdominis and internal oblique muscles demonstrated less extensibility in the direction transverse to muscle fibers than along fibers. Biaxial loading caused a stiffening effect that was greater in the direction along the fibers than transverse to the fibers. Furthermore, the abdominal muscle composite was less compliant than either muscle alone in the direction of the muscle fibers. Taken together, our data suggested that the internal abdominal composite tissue has complex mechanical properties that are dependent on the mechanical properties of internal oblique and transversus abdominis muscles.     

Features of the angioarchitectonics of the papillary muscles and the chordae tendineae of the human heart

In persons of mature, elderly and old age vascularization of the papillary muscles and tendinous chordae in the right and left cardiac ventricles has been studied depending on peculiarities of their structure and sources of their blood supply using injection, macro-microscopical, roentgenoangiographic methods, and silver nitrate impregnation. Certain data concerning the distribution zones in the papillary muscles of the coronary artery branches at various types of the cardiac blood supply are presented. Angioarchitectonics of the papillary muscles are described along their whole extention--in the basal area, in the middle part and at the apex. Architectonic peculiarities of the blood vessels in the muscular-tendinous part of the papillary muscles and in some tendinous chordae are described.     

Radionuclides in siberian Thymallus from radiation-contaminated area in the middle stream of the Yenisei River

Concentration of artificial radionuclides in bodies of arctic grayling from the radioactively contaminated zone of the Yenisei River in the vicinity of the Mining-and-Chemical Combine of Rosatom was investigated in 2007-2010. Gamma-spectrometric analysis revealed artificial radionuclides in all the organs and tissues of fish. The isotope composition was the most diverse (60Co, 65Zn, 85Sr, 99Mo, 106Ru, 137Cs, 144Ce) in internal organs of grayling. The activity of radionuclides increased in internal organs including liver and kidney and in the content of digestive tract of grayling during winter and spring, which coincided with the change in the feeding spectrum of grayling. The trophic transfer factor of radionuclides from zoobenthos (Philolimnogammarus spp.) to whole bodies and muscles of grayling was over 1 (1.8-2.4) only for natural radionuclide 40K. The trophic transfer of artificial radionuclides (60Co, 65Zn, 137Cs) to muscles and bodies of grayling was one-two orders of magnitude less effective.     

Scanning electron microscopic study of the capillary loops in the dermal papillae. Skin of the hand of the Japanese monkey (Macaca fuscata)

The microvasculature of the skin of the hand of Japanese monkeys was examined by means of scanning electron microscopy of corrosion casts. The vasculature of all areas of the skin of the hand was examined and divided into three structures excluding the nail bed: (1) In the ball of the finger, the typical structure of the capillary loops was studied. Capillary loops were formed out of not just one capillary vessel, but two or three vessels. Each capillary vessel arose and divided into several branches at the papilla, and they became descending limbs. After the loop passed a hairpin turn, the descending limbs were 1.5 times larger than the ascending limbs in the intrapapillary portion, and they became extrapapillary venules. The descending limbs connected with the postcapillary venules in the postpapillary portion and with the horizontal network. The postcapillary venules fused with each other (1-5 loops) to form the primary and secondary venous arcades. (2) In the thenar eminence, the capillary loops were a little lower, and their grooves were wider than in the ball of the finger. The characteristic structure in this area was the interpapillar capillary network. (3) In the lateral side of the finger, the number of capillary loops formed by the arterial capillary network of the subepidermal layer was smaller. The capillary loops here had the lowest height and a simple structure.     

Fine structure of anterior terminus of apical sense organ in Macracanthorhynchus hirudinaceus (Acanthocephala)

The apex of the proboscis of Macracanthorhynchus hirudinaceus is crowned by a cone-shaped projection with a small opening in its center. The bottom of this opening is the anterior terminus of the apical sensory organ. When viewed in transverse section, the anterior terminus of this organ appears as a series of distinct layers that encircle a central cone enclosing a complex arrangement of nerves and a sensory support cell duct. Four membrane-defined layers encircle the cone area. The outermost glycocalyx is morphologically identical with that described on the metasoma. The second layer, or tegument, is similar in appearance to that observed on the trunk except for the greater abundance of keratinlike bundles throughout. These bundles are also organized into a loose network along the inner tegumental membrane. The third layer, a latticework of fine filaments containing few organelles, has an erratic boundary that occasionally extends into layer 4. The area adjacent to the inner and outer boundary contains numerous vesicles. Layer 4 has 2 distinct zones. The outer contains filaments arranged as in circular muscle; whereas, the medial lacks such filaments but consists of a finely grained matrix. Radiating throughout both zones are numerous osmiophilic bundles of fibers. The cone at this level contains 8 branches of the apical sensory nerves that interdigitate with the duct from the sensory support cell. Numerous filaments and vesicles are associated with this complex.