The ultrastructure of the blood vessels of Branchiostoma lanceolatum (Pallas) (Cephalochordata)

Summary The ultrastructure of the blood vessels of Branchiostoma has been studied using selected characteristic vessels as examples. It is shown that the vessels are a part of the original blastocoelic cavity and are delimited either by the basal laminae of adjacent epithelia or by connective tissue developed in the blastocoelic space. A brief account of the kinds of connective tissue is given. The observed contractility of some vessels depends on two types of contractile filaments situated in the basal part of the surrounding coelomic epithelia. Amoebocytelike cells are present in the blood. They may sometimes lie in contact with the wall of the vessels or with each other, but never form a typical endothelium with junctional complexes and a basal lamina of its own. Actually, there is no endothelium in any part of the vascular system. It is suggested that the term endothelium should be reserved for a closed cellular lining (with junctions) on the luminal side of the vessel wall, standing on a basal lamina of its own and forming a barrier for the exchange between blood and surrounding tissue. It is concluded that the principal structure of the vascular system of Branchiostoma is different from that of vertebrates, but the same as that of other coelomate invertebrates. The blood vessels in these animals are typically delimited directly by a basal lamina secreted by epithelia (epidermal, coelomic or intestinal) lying peripheral to this lamina, and a true endothelium is not present (with a few questionable exceptions).Abbreviations ac atrial cavity - ace atrial epithelium - ao aorta - ap atrial plexus - ax axon bundle - bc blood cell - bl basal lamina - bl ₁ basal lamina of intestinal epithelium - bl ₂ basal lamina of visceral coelomic epithelium - bl ₃ basal lamina of parietal coelomic epithelium - bl ₄ basal lamina of atrial epithelium - bll basement lamella - cf contractile filaments - co coelomic cavity - coe coelomic epithelium - coe _p parietal coelomic epithelium - coe _v visceral coelomic epithelium - ct dense connective tissue - dv longitudinal dorsal vessel - ep epidermis - epe epipharyngeal groove epithelium - epg epipharyngeal groove - fb fibroblast (?) - fi collagen fiber - fl fibril layer - go gonad - hd hemidesmosome - ie intestinal epithelium - in intestine proper - ip intestinal plexus - iv afferent intestinal vessel - ld liver diverticulum - lu vascular lumen - me myocoelic epithelium - ml muscle lamella - mp myoseptal plexus - ms myoseptum - my myomer - myc myocoelic cavity - nc notochord - ns notochordal sheath - ph pharynx - suc subchordal coelom - sv subintestinal vessel - svv segmental ventral vessel - vv longitudinal ventral vessel Supported by a grant from the Danish Natural Science Research Council     

Modulation of swimming behavior in the medicinal leech

Expression of swimming in the medicinal leech (Hirudo medicinalis) is modulated by serotonin, a naturally occurring neurohormone. Exogenous application of serotonin engenders spontaneous swimming activity in nerve-cord preparations. We examined whether this activity is due to enhanced participation of swim motor neurons (MNs) in generating the swimming rhythm. We found that depolarizing current injections into MNs during fictive swimming are more effective in shifting cycle phase in nerve cords following serotonin exposure. In such preparations, the dynamics of membrane potential excursions following current injection into neuronal somata are substantially altered. We observed: 1) a delayed outward rectification (relaxation) during depolarizing current injection, most marked in inhibitory MNs; and 2) in excitor MNs, an enhancement of postinhibitory rebound (PIR) and afterhyperpolarizing potentials (AHPs) following hyperpolarizing and depolarizing current pulses, respectively. In contrast, we found little alteration in MN properties in leech nerve cords depleted of amines. We propose that enhanced expression of swimming activity in leeches exposed to elevated serotonin is due, partly, to enhancement of relaxation, PIR and AHP in MNs. We believe that as a consequence of alterations in cellular properties and synaptic interactions (subsequent paper) by serotonin, MNs are reconfigured to more effectively participate in generating and expressing the leech swimming rhythm.Abbreviations AHP Afterhyperpolarizing potential - DCC Discontinuous current clamp - DE Dorsal excitor motor neuron - DI Dorsal inhibitor motor neuron - IPSP Inhibitory postsynaptic potential - MN Motor neuron - PIR Postinhibitory rebound - VE Ventral excitor motor neuron - VI Ventral inhibitor motor neuron     

Ultrastructure of the Circulatory System of the Phoronid Phoronopsis harmeri Pixell, 1912. 2. Main vessels

The ultrastructure of the wall of the main blood vessels of the phoronid Phoronopsis harmeri is described. The walls of the lophophoral and left lateral vessels consist of myoepithelial cells of the coelomic lining (peritoneal cells), a thin basal lamina, and an incomplete endothelial lining. In the head region of the body, the wall of the medial vessel consists of myoepithelial cells of the coelomic lining (peritoneal cells), a basal lamina, and true muscular endothelial cells. The anterior part of the medial vessel functions as the heart. In the anterior part of the body, the medial vessel wall consists of five layers: the external nonmuscular coelothelium, a layer of the extracellular matrix, the internal muscular coelothelium, an internal layer of the extracellular matrix, and an incomplete endothelial lining. The complicated structure of the medial vessel wall may be explained by the superimposition of the lateral mesentery on the ordinary vessel wall.     

The gas bladder of Argentina silus L., with special reference to the ultrastructure of the gas gland cells and the countercurrent vascular bundles

Summary The orifice between the two chambers of the gas bladder in Argentina silus is surrounded by a sphincter muscle. Gas analyses of the gas bladder contents of fish from 400 meters depth give 0–1% carbon dioxide and 9–72% oxygen. Micro-retia mirabilia form a countercurrent vascular system, and the arterial component has peripherally a sphincter mechanism. The function of the glandular layer of the anterior chamber remains uncertain, but the structure indicates secretion into blood capillaries. The lining epithelium of the anterior chamber may secrete some substance into blood or directly into the lumen, which may be involved in a secretory mechanism. This conclusion is not supported by our histochemical tests. The posterior chamber has no micro-retia and the blood vessels have a different origin from those of the anterior chamber. The blood vessels form a plexus of capillaries or sinuses in contact with the flat lining epithelium, thus allowing gases to pass freely by diffusion. — The muscular layers of both chambers are innervated by catecholamine-containing nerve fibres.The investigation was supported by grants from the Swedish Natural Research Council (No. 99-35) and by the Faculty of Mathematics and Science, University of Lund.     

Fluorescence histochemical observations on the intrinsic adrenergic innervation and monoamine-containing cells of the feline pancreas,with special reference to the terminal main pancreatic duct of wirsung

Summary Intrinsic adrenergic innervation of the pancreas of the cat was studied using two fluorescence histochemical methods. Special emphasis was focused on the monoaminergic regulation of the mechanisms responsible for dynamically active suction-pressure pumping at the choledocho-pancreatico-duodenal junction, consisting of a labyrinthine reservoir chamber surrounded by a contractile mantle of smooth muscle, described recently (Kyösola, 1976). In that junction area, a rich distribution of single varicose fluorescing nerve fibers and small nerve fascicles, both free (i.e., unrelated to the blood vessels) and forming typical perivascular nerve plexuses, as well as large ganglia of nonfluorescing nerve cells surrounded by fluorescing baskets of varicose nerves were observed in the connective, fat, and pancreatic tissues, as well as between the smooth muscle bundles of the contractile smooth muscle mantle surrounding the reservoir chamber and its minor compartments. The epithelial lining of the labyrinthine duct system contained some solitary brightly yellow fluorescing enterochromaffin cells. In addition, two other categories of fluorescing cells were observed: (1) Small rounded cells with a relatively large rounded nucleus, and exhibiting a clearly bluish, usually granular, fluorescence varying from weak to intense; (2) Larger cells exhibiting quite a weak, clearly greenish to greenish-yellow fluorescence, either gathered in homogeneous clusters or mingled with the cells of the former type into heterogeneous cells clusters. These two cell types were clearly distinguishable from each other, but intermediate cell types were also seen. Thus, a continuous scale of fluorescing cells was observed, the color of the fluorescence varying from clearly bluish to greenish-yellow, the intensity of the fluorescence varying from intense to weak (respectively, in general), and the size ranging from small to large (respectively). These cells, probably heterotopic alpha cells of the islets of Langerhans, were frequently in quite close proximity to the smooth muscle surrounding the contractile labyrinthine system or its minor compartments. On the other hand, they were frequently in close proximity to quite large thin-walled sinusoid-type blood vessels. At least some of these fluorescing cells were surrounded by fluorescing varicose nerves, suggesting the existence of a neuroendocrine link. Scattered among these fluorescing cells, and also gathered into small clusters, were nonfluorescing nerve cells interconnected with fluorescing varicose nerves. The fluorescing cells of the endocrine pancreas, similarly, could be arbitrarily classified into two main categories, although intermediate cell types were observed as well: (1) Small rounded cells with a large, ovoid to rounded, centrally placed nucleus, and exhibiting a moderate to intense granular cytoplasmic fluorescence. The color of the fluorescence varied from yellow-green to blue-green, and there were considerable differences also in the fluorescence intensity. (2) Mixed irregularly with the type (1) cells were cells with more or less the same cytologic characteristics, but slightly larger, and exhibiting a rather homogeneous weak yellow fluorescence. Sometimes the fluorescence intensity was so weak that it was hardly discernible. These cells were packed densely and irregularly with the type (1) cells within the clusters, and no clear-cut spatial organization between these two cell types was observed. In the wall of the main pancreatic duct of Wirsung, both free and perivascular fluorescing nerves were seen within the different layers, including the (distally incomplete) smooth muscle layer. The epithelial lining of the duct contained enterochromaffin cells, sometimes located so deeply in the epithelial invaginations that they were in close proximity to the smooth muscle. The distribution of fluorescing nerves in the exocrine pancreas was sparse. Typical enterochromaffin cells exhibiting a bright yellow granular cytoplasmic fluorescence were scattered either solitarily or in small groups in the epithelial lining of the acini and of the small excretory ducts. Blue-green fluorescing varicose adrenergic axons were some-times seen to connect enterochromaffin cells or groups of them located in different acini. Scattered within the parenchyme of the exocrine pancreas were clusters of nonfluorescing nerve cells surrounded by typical baskets of fluorescing varicose terminal ramifications of adrenergic axons. In the endocrine pancreas, similarly, only a relatively sparse distribution of fluorescing nerves was observed among the islet cells and surrounding clusters of them. However, groups of islet cells were observed to be interconnected by fluorescing varicose nerves coursing through or near nonfluorescing ganglia, suggesting an integrative neural connection between pancreatic islets and nonadrenergic ganglia via adrenergic nerves.     

Ultrastructure of the body cavity lining in a secondary acoelomate,Microphthalmus cf. Listensis westheide (Polychaeta: Hesionidae)

The organization of the body cavity lining in selected regions of the juvenile and adult of the interstitial hesionid polychaete Microphthalmus cf. listensis is described. Tissues comprising the body cavity lining in the juvenile consist of somatic and splanchnic circular and longitudinal muscles and undifferentiated cells. Somatic and splanchnic cell layers exhibit epithelial ( = eucoelomate) organization in the pharyngeal region. In the midbody, some undifferentiated cells exhibiting mesenchymal organization persist among the epithelially organized somatic and splanchnic cells, forming a gradation between eucoelomate and acoelomate tissue organizations. A coelomic cavity is absent. Tissues comprising the body cavity lining of the adult consist of somatic and splanchnic circular and longitudinal myocytes and coelenchymal cells. Coelenchymal cells are shown from serial section analysis to be mesenchymal in organization and derived from the somatic peritoneum. A 30–65-nm coelomic cavity lies between the apices of somatic and splanchnic cell layers in the pharyngeal region. In the anterior setigerous segments, the coelom is reduced to a narrow cavity surrounded by coelenchymal cells lying midventrally between the paired ejaculatory ducts. There is a regional obliteration of the splanchnic musculature in the posterior segments so that apices of the coelenchymal cells lie in direct apposition to the basal extracellular matrix of the gut. The coeom is only present middorsally as a 0.7-μm-wide cavity. Although the coelomic cavity is highly reduced in the adult, the body cavity lining still reveals its origin from the epithelial ( = eucoelomate) organization. The findings of this study illustrate possible organizational intermediates in the evolution of the acoelomate from the eucoelomate condition in annelids.     

Primordial germ cells and early stages of oogenesis in Ophryotrocha puerilis (Polychaeta,Dorvillediae)

Summary Each setigerous segment of the protandric polychaete Ophryotrocha puerilis contains two primordial germ cells. A ventral furrow in the gut wall together with the peritoneal lining of the gut forms a genital blood vessel. The gonocytes are located within the peritoneum of this genital blood vessel. At sexual maturity the gonocytes undergo a proliferation cycle, the first division of which gives rise to a cell which is extruded into a forming outpocketing of the coelomic lining. The stem cell remains within the peritoneum. Inside the forming gonad the detached cell goes through a series of four mitotic divisions. The resulting 16 cells are interconnected by cytoplasmic bridges. These bridges are arranged in a very regular pattern which allows the mitotic cycles to be followed. While remaining still within the gonad the 16 cells begin to synthesize yolk and to take up exogenous yolk precursors. At this stage a differentiation into oocytes and nurse cells becomes visible. The oocytes deposit yolk platelets of the definitive size whereas the polyploid nurse cells produce only small yolk bodies that are passed to the adjacent oocytes. In a later stage the cell bridges between adjacent nurse cells are cut and pairs of one oocyte and one nurse cell are released to the coelomic cavity during breakdown of the gonadal sac. Oocyte-nurse cell-complexes then freely float in the coelomic fluid. The proliferation of gonadal cells is well synchronized within one segment. In anterior segments, however, gonadal proliferation usually begins earlier than in posterior segments but smaller oocytes in posterior segments catch up within a few days. Finally a batch of oocytes is produced in which all the oocytes are of the same size (120 m). The origin of the primordial germ cells remains unknown.     

Ultrastructure of muscle cells in Siboglinum fiordicum (Pogonophora)

Two different muscle types are found in the body of Siboglinum fiordicum: body wall muscle and blood vessel muscle. Both are of a myomesothelial type. The myofibrils of the body wall muscle are non-striated and consist of thick and thin myofilaments. Scattered dense bodies and attachment plaques are described. The sarcoplasmic reticulum forms a three-dimensional network in the myofibrils and only peripheral couplings are observed. The thick filaments are of a paramyosin type and have a diameter ranging from 400-1500 A. The blood vessels muscle is non-striated, but sometimes a sarcomere-like organization has been observed. Both thick and thin filaments are present. The thick filaments have a diameter of 250-400 A and lack transverse striations. Dense bodies and attachment of plaques are few. The sparse sarcoplasmic reticulum is restricted to the myofibril periphery where it makes peripheral couplings with sarcolemma. The luminal surface of the vessels is lined by a basal lamina with collagen-like inclusions. No endothelium is found. The body wall muscle and the blood vessel muscle are compared with other muscle types described in invertebrates.     

Circulation,metabolic rate,and body size in mammals

Summary This paper attempts to explain Kleiber's rule, which relates metabolic rate of mammals to their body mass, from the structure and function of the blood circulation system.Abbreviations a scaling factor - fractal dimension - hydrodynamic conductivity - l _n length of an arterial blood vessel at bifurcation level n - M body mass - N maximal number of bifurcation levels - p pressure - Q flow - r size of Bohr effect - r _n radius of an arterial blood vessel at bifurcation level n - V volume - VO ₂ rate of oxygen unloading - Z _n number of arterial blood vessels at bifurcation level n     

The anatomy and ultrastructure of the antennal circulatory organs in the cockchafer beetle Melolontha melolontha L. (Coleoptera,Scarabaeidae)

Summary The antennal circulatory organs of Melolontha are described for the first time. They consist of small sac-like ampullae located near the base of each antenna and connected to a long non-muscular antennal blood vessel. Small branches of this vessel extend into each lamella of the antennal club and open out distally. The membranous wall of the ampulla provides no contractile structures. An outer adjacent compressor muscle is responsible for the pumping movements of the ampulla and antagonist to it is an obviously elastic connective tissue band. The position of this elastic band causes the uncontracted muscle to be pulled away from the ampulla. As a consequence blood can enter the dilated ampulla through a valvular ostium. The functional type of the antennal circulatory organs in Melolontha is compared to that found in other insects and their histologic structure is interpreted in relation to mechanical and hemodynamical aspects. Furthermore the possible function of the antennal hearts in connection with the spreading of its lamellate antennal club is discussed.Dedicated to Prof. Dr. M. Gersch's 70th birthday.Supported by project 3,106 of the Fonds zur Förderung der wissenschaftlichen Forschung in Österreich     

波纹盘肠溞(甲壳纲、双甲目)的重新描述及其生态学资料

波纹盘肠溞(Chydorus undulatus Chiang,1963)系蒋燮治1定名的枝角类新种。其主要特征是壳瓣腹缘内面具有双行排列整齐的拱型下陷。标本采集于1956年8月,祇在青海省的隔湖、倒淌河及其附近的沼地等很少处所发现。二十余年来尚未见他处报道。中国动物志已将这种枝角类列为我国的特有种2,甚至是青藏高原的特产种1。       

Ontogeny of microbodies (glyoxysomes) in cotyledons of dark-grown watermelon (Citrullus vulgaris Schrad.) seedlings

The development of glyoxysomal marker enzyme activities and concomitant ultrastructural evidence for the ontogeny of glyoxysomes has been studied in cotyledons of dark-grown watermelon seedlings (Citrullus vulgaris Schrad., var. Florida Giant). Catalase (CAT, EC 1.11.1.6) was stained in glyoxysomal structures with the 3,3-diaminobenzidine procedure. Serial sections and high-voltage electron microscopy were used to analyze the three-dimensional structure of the glyoxysomal population. With early germination CAT was localized in three distinct cell structures: spherical microbodies already present in freshly imbibed cotyledons; in appendices on lipid bodies; and in small membrane vesicles between the lipid bodies. Due to their ribosome-binding capacity, both appendices and small vesicles were identified as derivatives of the endoplasmic reticulum (ER). In the following period, glyoxysome formation and lipid body degradation were found to be inseparable processes. The small CAT-containing vesicles attach to a lipid body on a restricted area. Both lipid body appendices and attached cisternae enlarge around and between tightly packed lipid bodies and eventually become pleomorphic glyoxysomes with lipid bodies entrapped into cavities. The close contact between lipid body and glyoxysomes is maintained until the lipid body is digested and the glyoxysomal cavity becomes filled with cytoplasm. During the entire period of increase in glyoxysomal enzyme activities, no evidence was obtained for destruction of glyoxysomes, but small CAT-containing vesicles were observed from day 2 through day 6 after imbibition, indicating a continuous de novo formation of glyoxysomes. This study does not substantiate the hypothesis that glyoxysomes bud directly from the ER. Rather, ER-derivatives, e.g., lipid body appendices or cisternae attached to lipid bodies are interpreted as being glyoxysomal precursors that grow in close contact with lipid bodies both in volume and surface membrane area.Abbreviations CAT catalase - DAB 3,3 diaminobenzidine tetrahydrochloride - ER endoplasmic reticulum - GOX glycolate oxidase - HPR hydroxypyruvate reductase - HVEM high-voltage electron microscopy - ICL isocitrate lyase - MS malate synthase - RER rough endoplasmic reticulum In the figures bars represent 0.1 m (if not stated otherwise)     

The Fine Structure of Some Blood Vessels of the Earthworm, Eisenia foetida

The fine structure of the main dorsal and ventral circulatory trunks and of the subneural vessels and capillaries of the ventral nerve cord of the earthworm, Eisenia foetida, has been studied with the electron microscope. All of these vessels are lined internally by a continuous extracellular basement membrane varying in thickness (0.03 to 1 µ) with the vessel involved. The dorsal, ventral, and subneural vessels display inside this membrane scattered flattened macrophagic or leucocytic cells called amebocytes. These lie against the inner lining of the basement membrane, covering only a small fraction of its surface. They have long, attenuated branching cell processes. All of these vessels are lined with a continuous layer of unfenestrated endothelial cells displaying myofilaments and hence qualifying for the designation of "myoendothelial cells." The degree of muscular specialization varies over a spectrum, however, ranging from a delicate endowment of thin myofilaments in the capillary myoendothelial cells to highly specialized myoendothelial cells in the main pulsating dorsal blood trunk, which serves as the worm's "heart" or propulsive "aorta." The myoendothelial cells most specialized for contraction display well organized sarcoplasmic reticulum and myofibrils with thick and thin myofilaments resembling those of the earthworm body wall musculature. In the ventral circulatory trunk, circular and longitudinal myofilaments are found in each myoendothelial cell. In the dorsal trunk, the lining myoendothelial cells contain longitudinal myofilaments. Outside these cells are circular muscle cells. The lateral parts of the dorsal vessels have an additional outer longitudinal muscle layer. The blood plasma inside all of the vessels shows scattered particles representing the circulating earthworm blood pigment, erythrocruorin.     

The fine structure of cephalopod blood vessels III. Vessel innervation

Summary The cephalic aorta of Octopus vulgaris has a fairly complete endothelium lining the lumen, a thick complete basement membrane, a layer of circularly orientated and a layer of longitudinally orientated muscle fibres. Presumptive synaptic endings are of two types. In the circular muscle, axons containing vesicles, contact club-shaped projections of the muscle. The gap between the pre- and postsynaptic membranes is less than 100 Å and in some places apparently forms a tight junction. The second type of ending has been found in the longitudinal muscle; here axons full of vesicles end on the muscle. The ending is enclosed by a mesaxon of muscle and the synaptic gap is approximately 100 Å. In the smaller blood vessels, axons end on myofilament-containing pericytes of blood vessels (equivalent to small arterioles). The endings contain vesicles and have a synaptic gap of 100 Å. Only some of the pericytes seem to be innervated and transmission between one pericyte to another may be mediated by specialized junctions between the cells. The smaller non-myofilament containing vessels (equivalent to capillaries) are not thought to be innervated.We would like to thank Professor J. Z. Young and Dr. E. G. Gray for advice and encouragement, Mrs. Jane Astafiev for drawing Figs. 1 and 12, Mr. S. Waterman for photography, and Miss Cheryl Martin for secretarial assistance.     

Cell sources of liver development

The work is devoted to consequent expression of different cell types' protein markers such as vimentin, desmin, cytokeratins 7, 18, 19, stem cell markers CD34 and Bcl-2 at early stages of human prenatal development. Desmin was revealed in sinusoidal liver cells on 3.5-12 weeks of gestation, in mesenchymal cells of ventral mesentery and hepatoblasts on the 4-7 accordingly. During hepatic period of blood formation such desmin positive sinusoidal cells were found to be located close to blood cells. So called "cholangio-" cytokeratins 7 and 19 showed different expression, the first one was found only in cholangiocytes, while cytokeratin 19 existed in hepatoblasts as well until week 15-16 of prenatal development. Mesenchymal cells of ventral mesentery are positive for cytokeratins 18 and 19 even brighter than hepatoblasts in the 4-7 weeks of gestation. Bcl-2 expression was seen in the same periods in most sinusoidal and mesenchymal cells of ventral mesentery. CD34 positive cells are strongly depicted in liver sinusoids from 4th until 9th weeks of gestation, but probably they are not a source of hepatocytes' development in embryonic ontogenesis. Ventral mesentery mesenchyme was negative for this very marker. These results let us suppose that hepatocytes and cholangiocytes may develop from quite different embryonic sources: cholangyocytes grow exceptionally from duodenum epithelial cells, while there is a strong possibility that hepatoblasts formation occurs with participation of mesenchymal cells.     

Elektronenmikroskopie am sensorischen Apparat der Fadenhaare auf den Cerci der Schabe Periplaneta americana

Summary The filiform hairs are sensitive for week air currents. Each receptor unit consists of an elastically inserted cuticular hair, a single sensory cell, and a surrounding fluid filled cavity lined partly by the cuticle and partly by special lining cells, exhibiting many villiform protrusions. The mentioned cavity — at least by adult cockroaches — is extracellular and the authors suggest the nomenclature receptorlymph cavity. The expression vacuole of the trichogen cell should not be used.The distal process of the sensory cell protrudes into the base of the cuticular hair and contains a tubular body consisting of more than 1000 microtubuli which, in the resting position of the hair, are slightly bent.It is suggested that the stimulus is transmitted to the tubular body, where bending of the tubuli causes depolarization and straigthening repolarization, when bending the hair in opposite directions.

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Mit Unterstützung durch die Deutsche Forschungsgemeinschaft.

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Mit Unterstützung durch: Grant No. NB 3956-04-05 des US Public Health Service; Swedish Medical Research Council B 67-12 x-720-02; Stiftelsen Therese och Johan Andersson Minne.     

Immunohistochemical localization of 14 kDa β-galactoside-binding lectin in various organs of rat

Summary Immunohistochemical localization of 14 kDa -galactoside-binding lectin in various organs of adult rat was achieved using a monospecific antibody raised against lectin purified from rat lung. The antibody-stained cells were formed into small aggregates, thin fascicles, or thick bundles in the walls of blood vessels, gastrointestinal tracts and urogenital organs. From the patterns of distribution, as well as their organization, these immunoreactive cells were regarded as smooth muscle cells. This was confirmed by a double immunofluorescence study using a mixture of anti 14 kDa lectin and anti -smooth muscle-specific actin antibodies. Strong 14 kDa lectin immunoreactivity was seen in the pericellular matrix of smooth muscle cells in intact organs as well as in detergent-treated organs from which all cellular components were extracted. From these findings, it is suggested that the 14 kDa lectin may be externalized by smooth muscle cells into their pericellular matrix and participate in the crosslinking of the complementary glycoconjugate(s) localized at that site. The macromolecular complex of glycoconjugates thus formed around smooth muscle cells may play a role in anchoring smooth muscle cells to the pericellular connective tissue thereby permitting the force of muscle contraction to be efficiently transmitted to the surrounding connective tissue proper.     

Contrast Enhanced Vessel Imaging using MicroCT

Microscopic computed tomography (microCT) offers high-resolution volumetric imaging of the anatomy of living small animals. However, the contrast between different soft tissues and body fluids is inherently poor in micro-CT images ¹. Under these circumstances, visualization of blood vessels becomes a nearly impossible task. To overcome this and to improve the visualization of blood vessels exogenous contrast agents can be used. Herein, we present a methodology for visualizing the vascular network in a rodent model. By using a long-acting aqueous colloidal polydisperse iodinated blood-pool contrast agent, eXIA 160XL, we optimized image acquisition parameters and volume-rendering techniques for finding blood vessels in live animals. Our findings suggest that, to achieve a superior contrast between bone and soft tissue from vessel, multiple-frames (at least 5-8/ frames per view), and 360-720 views (for a full 360° rotation) acquisitions were mandatory. We have also demonstrated the use of a two-dimensional transfer function (where voxel color and opacity was assigned in proportion to CT value and gradient magnitude), in visualizing the anatomy and highlighting the structure of interest, the blood vessel network. This promising work lays a foundation for the qualitative and quantitative assessment of anti-angiogenesis preclinical studies using transgenic or xenograft tumor-bearing mice.Download video file.^{(37M, mov)}     

Anatomical and gravitational influences on cardiac displacement in snakes (Lepidosauria,Serpentes)

Summary Radiographs of live, unanesthetized snakes were used to document the position of the heart in the body cavity during horizontal, head-up, and head-down postures. The extent of cardiac displacement observed during these postural changes differed substantially among the snakes examined, ranging from virtually none in a thin-bodied arboreal snake to as much as three vertebral lengths (=half the length of the heart) in a heavy-bodied terrestrial Crotalus. The basis of this differential cardiac displacement is attributed to the anatomical packaging of the pericardial sac. In some snakes the pericardial sac is loosely suspended in the body cavity by the great vessels and connective tissue sheets. In contrast, in other snakes the pericardial sac is buttressed against the body wall, the lung, or the liver. We hypothesize that cardiac displacement during postural change may alter the pattern of blood flow in the aortae of snakes.     

Possible sites of ultrafiltration in Tubifex tubifex Müller (Annelida,Oligochaeta)

Summary The endothelia of Tubifex tubifex Müller consist of myoendothelial cells, chloragocytes, or podocytes. The latter seem to occur only as windows on the ventral vessel which has an endothelium of myoendothelial cells elsewhere. The podocytes are large cells, with several processes on the inner side which ramify into several pedicels. These are aligned upon the outside of the basement membrane which lines the inside of the endothelium. The gaps between adjacent pedicels are about 40 nm wide. In capillaries fenestrated endothelia occur with irregular spacings measuring up to 0.4–1 m. A diaphragm in podocytes or capillary fenestrations do not seem to exist. The basement membrane is the only continuous layer lining the blood vessels and capillaries of Tubifex with a rather uniform diameter in the range of 50 nm. It is the only permeability barrier between blood and coelomic fluid.