Localization of the haemopoietic tissue of polychaete annelids. II. Site of chlorocruorin synthesis (author's transl)

The perivasal tissue of some blood vessels (antero-lateral vessels of Pomatoceros triqueter, ventral and lateral vessels of Sabella pavonina) shows a remarkable quantity of iron and pseudo-peroxidase activity. At the EM level, this tissue is characterized by numerous dense DAB positive inclusions and well developed granular endoplasmic reticulum and Golgi. Its function in chlorocruorin synthesis is discussed.     

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

Summary The ultrastructure of the blood vessels in the caudal region of Branchiostoma is described in specimens injected with indian ink. None of the vessels have endothelial cells delimiting the luminal surface. The vessels are delimited either by dense connective tissue or by the characteristic basement lamella underneath the basal lamina of the myocoelic epithelium. It is proposed that the main blood flow in the caudal region follows different pathways depending on the activity of the animal. During swimming the muscle activity of the caudal muscles may have the effect that more blood flows from the aorta to the myoseptal plexi and is drained to the caudal vessel. In the resting animal it is possible that the blood flow through the myosepta is insignificant, and that the caudal blood flow is more or less restricted to the direct connections between the aorta and the caudal vessel: the dorsoventral anastomosis and the segmental connecting vessels.Supported by a grant from the Danish Natural Science Research Council     

An inhibitor of macrophage arginine transport and nitric oxide production (CNI-1493) prevents acute inflammation and endotoxin lethality.

BACKGROUND: Nitric oxide (NO), a small effector molecule produced enzymatically from L-arginine by nitric oxide synthase (NOS), is a mediator not only of important homeostatic mechanisms (e.g., blood vessel tone and tissue perfusion), but also of key aspects of local and systemic inflammatory responses. Previous efforts to develop inhibitors of NOS to protect against NO-mediated tissue damage in endotoxin shock have been unsuccessful, largely because such competitive NOS antagonists interfere with critical vasoregulatory NO production in blood vessels and decrease survival in endotoxemic animals. Accordingly, we sought to develop a pharmaceutical approach to selectively inhibit NO production in macrophages while sparing NO responses in blood vessels. MATERIALS AND METHODS: The process of cytokine-inducible L-arginine transport and NO production were studied in the murine macrophage-like cell line (RAW 264.7). A series of multivalent guanylhydrazones were synthesized to inhibit cytokine-inducible L-arginine transport. One such compound (CNI-1493) was studied further in animal models of endothelial-derived relaxing factor (EDRF) activity, carrageenan inflammation, and lethal lipopolysaccharide (LPS) challenge. RESULTS: Upon activation with cytokines, macrophages increase transport of L-arginine to support the production of NO by NOS. Since endothelial cells do not require this additional arginine transport to produce NO, we reasoned that a competitive inhibitor of cytokine-inducible L-arginine transport would not inhibit EDRF activity in blood vessels, and thus might be effectively employed against endotoxic shock. CNI-1493, a tetravalent guanylhydrazone, proved to be a selective inhibitor of cytokine-inducible arginine transport and NO production, but did not inhibit EDRF activity. In mice, CNI-1493 prevented the development of carrageenan-induced footpad inflammation, and conferred protection against lethal LPS challenge. CONCLUSIONS: A selective inhibitor of cytokine-inducible L-arginine transport that does not inhibit vascular EDRF responses is effective against endotoxin lethality and significantly reduces inflammatory responses.     

Morphofunctional characteristics of the vascular endothelium in the common leech (Clepsina complanta)

The electron microscopic investigation has revealed in the body of the leech two types of vessels, that together with common signs possess a number of peculiarities in composition of endothelial cells. These vessels have different level of organization: the vessels of the first type, concerning the parenchyma of the leech, are nutritive, and the vessels of the second type combine capacitance and transport functions and are the place of hemolymph renovation at the expense of an active metabolic and synthetic activity of the endothelial cells. A fact is stated concerning a specific position of mitochondria in the endotheliocytes of the second type vessels: from the vessel's lumen they are not covered with plasmolemma along their whole extent and come into an immediate contact with hemolymph. Therefore, a hypothesis is suggested on functional activity of the endothelial cell mitochondria in the second type vessels. Presumptive differentiation of the two major vessels of the leech body makes it possible to suppose that there exist functional predecessors of the vessels of branchial and pulmonary type, that is vessels of lesser and greater circulation.     

Lymphatic vessels in lungfishes (Dipnoi)

 Lymphatic capillaries are distributed throughout the body of lepidosirenid and protopterid Dipnoi, except in the central nervous system. They form small, interconnected units which are individually evacuated into nearby blood capillaries by lymphatic micropumps. The number of lymphatic micropumps varies considerably in different parts of the body. In fin areas, 30–50 per mm³ tissue may be considered normal in Protopterus annectens, but up to 105 per mm³ have been counted in an anterior fin of Lepidosiren paradoxa. Lymphatic capillaries are formed by thin endothelial cells with fine processes into the surrounding interstitial space. Occasionally there is a faint, discontinuous basal lamina. Pericytes, however, are completely absent. Microfibrils establish contact between endothelial cells and surrounding connective tissue fibers. The lymphatic micropumps are essentially spherical, contractile organs of 35–55 μm in diameter. Their central lumen is lined by extensions of a single endothelial cell. Additional endothelial cells form inflow and outflow valves. The endothelial layer is surrounded by a single large, highly specialized muscle cell. This spherical muscle cell has many perforations, allowing the passage of thin outward processes of the endothelial cell which form part of the suspension apparatus of the lymphatic micropump. The muscle cell establishes a specialized end-to-end contact between opposing parts of its own cell membrane. This contact is very similar to an intercalated disc in vertebrate heart muscle. Each lymphatic micropump is suspended within a cell-free tissue area by microfibrils which radiate from the lymphatic micropump into the surrounding connective tissue. The microfibrils are occasionally reinforced by single collagen fibers. The cell-free area around each lymphatic micropump appears as a bright halo in both light and electron micrographs. No type of lymphatic vessel other than lymphatic capillaries could be detected in the Dipnoi studied. Lepidosireniform Dipnoi are the only Vertebrata besides the Tetrapoda in which lymphatic vessels and characteristic lymphatic pumps have been documented. In addition, these Dipnoi and all Tetrapoda share the same overall design of blood circulation, which is not divided into a primary and a secondary system of vessels, as it is in Actinopterygii, Chondrichthyes, and Agnatha. Since there are primary and secondary blood vessels in the gills of Latimeria chalumnae, while the existence of lymphatic vessels has not been confirmed, general angioarchitecture should be taken into account as an important character when phylogenetic relationships among extant Sarcopterygii are discussed. Accepted: 7 October 1997     

Induction of oxidative stress by homocyst(e)ine impairs endothelial function

Previous studies have demonstrated a relationship between hyperhomocysteinemia and endothelial dysfunction, reduced bioavailability of nitric oxide, elastinolysis and, vascular muscle cell proliferation. In vivo decreased nitric oxide production is associated with increased matrix metalloproteinase (MMP) activity and formation of nitrotyrosine. To test the hypothesis that homocysteine neutralizes vascular endothelial nitric oxide, activates metalloproteinase, causes elastinolysis and vascular hypertrophy, we isolated aortas from normotensive Wistar rats and cultured them in medium containing homocysteine, and calf serum for 14 days. Homocysteine-mediated impairment of endothelial-dependent vasodilatation was reversed by co-incubation of homocysteine with nicotinamide (an inhibitor of peroxinitrite and nitrotyrosine), suggesting a role of homocysteine in redox-mediating endothelial dysfunction and nitrotyrosine formation. The Western blot analysis, using anti-nitrotyrosine antibody, on aortic tissue homogeneates demonstrated decreased nitrotyrosine in hyperhomocysteinemic vessels treated with nicotinamide. Zymographic analysis revealed increased elastinolytic gelatinase A and B (MMP-2, -9) in homocysteine treated vessels and the treatment with nicotinamide decreases the homocysteine-induced MMP activation. Morphometric analyses revealed significant medial hypertrophic thickening (1.4 +/- 0.2-fold of control, P = 0.03) and elastin disruption in homocysteine-treated vessels as compared to control. To determine whether homocysteine causes endothelial cell injury, cross-sections of aortas were analyzed for caspase activity by incubating with Ac-YVAD-AMC (substrate for apoptotic enzyme, caspase). The endothelium of homocysteine treated vessels, and endothelial cells treated with homocysteine, showed marked labeling for caspase. The length-tension relationship of homocysteine treated aortas was shifted to the left as compared to untreated aortas, indicating reduced vascular elastic compliance in homocysteine-treated vessels. Co-incubation of homocysteine and inhibitors of MMP, tissue inhibitor of metalloproteinase-4 (TIMP-4), and caspase, YVAD-CHO, improved vascular function. The results suggest that alteration in vascular elastin/collagen ratio and activation of MMP-2 are associated with decreased NO production in hyperhomocysteinemia.     

Interrelationships between developing oocytes and ovarian tissues in the chiton Sypharochiton septentriones (Ashby) (Mollusca, Polyplacophora)

Oogenesis and the relationships between oocytes and other ovarian tissues have been studied in Sypharochiton septentriones. The ovarian tissues were examined by electron microscopy and by histochemical methods. The sac-like ovary is dorsal, below the aorta, and opens to the exterior by two posterior oviducts. Ventrally, the ovarian epithelium is folded inwards to form a series of plates of tissue, which support the developing ova. Each ovum is attached to a tissue plate by a stalk, the plasma membrane of which is bathed by the blood in the tissue plate sinus. Dorsally, ciliated vessels from the aorta enter the ovary and open into blood sinuses in the top of the plates. After each germinal epithelial cell rounds up to become a primary oogonium, it undergoes four mitotic divisions to give rise to a cluster of 16 secondary oogonia. Of these, the outer ones become follicle cells and the inner ones become oocytes. As in other molluses, the increases in nuclear and nucleolar volume are relatively greatest towards the end of previtellogenesis, when chromosomal and nucleolar activity are most intense. This phase of activity is accompanied by a great increase in cytoplasmic basophilia. Subsequently this basophilia is decreased during vitellogenesis, when chromosomal and nucleolar activity diminish. Fluid filled interstices appear in the cytoplasm during early vitellogenesis. Protein yolk deposition is associated with these interstices, but the lipid yolk appears to arise de novo. The follicle cells do not appear to be directly involved in oocyte nutrition. At times during oogenesis, certain manifestations of polarity can be found in the oocyte. This polarity is based on an apical-basal axis and can be related to the nutritive source of the oocyte, namely the blood which bathes the plasma membrane of the oocyte in the stalk. Numerous granulated cells are present in the ovarian tissue plates and ventral epithelium as storage cells containing lysosomes, and they are capable of phagocytosis and micropinocytosis of extracellular material. A scheme is outlined whereby reserves in these cells may be incorporated into the oocyte cytoplasm. Lysosomal activity is responsible for autolysis of the cells as well as resorption of unspawned ova.     

Vasoactive intestinal polypeptide (VIP)-like immunoreactivity in salivary glands.

VIP-like immunoreactivity was found in rat, cat and human salivary glands at a concentration of 17.0 – 29.3 pmol/g of tissue. The immunoreactivity was localised by immunocytochemistry in beaded nerve fibres which occurred in association with secretory acini, ducts, blood vessels and larger nerves. In salivary glands VIP may act as a neurotransmitter or neuromodulator involved in the regulation of blood flow and in the composition and volume of saliva.     

Control of ketogenesis from amino acids. IV. Tissue specificity in oxidation of leucine, tyrosine, and lysine.

In vitro and in vivo studies were made on the tissue specificity of oxidation of the ketogenic amino acids, leucine, tyrosine, and lysine. In in vitro studies the abilities of slices of various tissues of rats to form 14CO2 from 14C-amino acids were examined. With liver, but not kidney slices, addition of alpha-ketoglutarate was required for the maximum activities with these amino acids. Among the various tissues tested, kidney had the highest activity for lysine oxidation, followed by liver; other tissues showed very low activity. Kidney also had the highest activity for leucine oxidation, followed by diaphragm; liver and adipose tissue had lower activities. Liver had the highest activity for tyrosine oxidation, but kidney also showed considerable activity; other tissues had negligible activity. In in vivo studies the blood flow through the liver or kidney was stopped by ligation of the blood vessels. Then labeled amino acids were injected and recovery of radioactivity in respiratory 14CO2 was measured. In contrast to results with slices, no difference was found in the respiratory 14CO2 when the renal blood vessels were or were not ligated. On the contrary ligation of the hepatic vessels suppressed the oxidations of lysine and tyrosine completely and that of leucine partially. Thus in vivo, lysine and tyrosine seem to be metabolized mainly in the liver, whereas leucine is metabolized mostly in extrahepatic tissues and partly in liver. Use of tissue slices seems to be of only limited value in elucidating the metabolisms of these amino acids.     

Arterial and venous vasculature of the heart of the beluga whale (Delphinapterus leucas)

The arteries and veins of the heart of the beluga whale (Delphinapterus leucas) are described from the dissection of nine specimens. The arterial distribution is composed of the basic mammalian pattern of two major vessels, the left and right coronary arteries, which supply the cardiac tissue. The venous drainage is provided by three major systems which are the great, middle, and small cardiac veins. The vascular characteristics of the heart of the beluga whale are the marked sinuosity of both coronary arteries and their main branches, the numerous large interarterial anastomoses between major vessels, and the duplication of vessels in parallel branches. These characteristics are discussed in functional terms and correlated with the diving ability of the species.     

植物血凝素对兴国红鲤头肾和脾脏的比较组织学研究

PHA注射前后兴国红鲤头肾和脾脏结构基本相同。红鲤头肾有被膜,为淋巴样组织,由许多血管,血窦和淋巴索组成,脾脏是实质性器官,淋巴细胞聚集成团,有弥散的胰腺组织渗入,注射PHA后头肾和脾脏内的大淋巴细胞,小淋巴细胞,巨噬细胞以及原始型细胞显著增加,而粒细胞数量变化不明显。     

Spleen of the snake (Elaphe climacophora) and intrasplenic vascular architecture

The spleen of the blue-green snake (Elaphe climacophora) lies at the head of the pancreas and is separated from it by a fibrous capsule. A hilus is not clearly distinguished. Arteries and veins enter or leave the spleen through the capsule, but no collateral relationship is observed between these vessels. Histologically, the spleen consists of the capsule-septal tissue, lymphoid tissue (the white pulp), and a fibrous zone (the perilymphoid fibrous zone: PLFZ) around the lymphoid tissue that includes many small veins. The PLFZ probably represents the involuted red pulp. The border between the white pulp and PLFZ is unclear in routine histological sections due to diffuse infiltration of lymphocytes into the latter region, but the border could be distinguished clearly in silver-impregnated specimens. Arteries enter the spleen, run within the septa, and divide into terminal arteries in the lymphoid tissue that form end branches. There are no ellipsoids around the terminal arteries. The end branches communicate with veins of the PLFZ through transitional vessels within the lymphoid tissue (closed circulation). The veins of the PLFZ anastomose with drainage veins in the capsule. The snake spleen retains the basic histological characteristics of a spleen and is morphologically distinguishable from a lymph node. It may represent an extreme example of a spleen modified by the remodelling of the intrasplenic vasculatures during evolution. © 1995 Wiley-Liss, Inc.     

EMBRYOGENESIS AND SEEDLING DEVELOPMENT IN CASSIPOUREA ELLIPTICA (SW.) POIR. (RHIZOPHORACEAE)

Embryogenesis in Cassipourea elliptica (Sw.) Poir, begins with a first division of the zygote which may be oriented transversely, obliquely, or rarely longitudinally. The orientation of the second division is also variable. Though the differentiation of suspensor and embryo proper occurs early, some derivatives of the terminal cell sometimes contribute to the suspensor. Provascular tissue “differentiates” after the initiation of the cotyledons. The radicle apical meristem originates subterminally, 5–10 cell layers from the juncture of the embryo proper and the suspensor. After germination, during early seedling establishment, radicle apical organization is of an unspecialized, columellate type. Vascular differentiation occurs before germination, and there are two loci of initial xylem differentiation: one in the hypocotyl and another in the median trace of the cotyledons. After germination, additional xylem differentiates de novo (without lateral or longitudinal continuity with already-mature vessels) inside the arcs of phloem in the hypocotyl, a pattern reported in few angiosperms. The cotyledonary node is one-trace, unilacunar.     

Morphology of central compartment and vasculature of the gills of Lepidosiren paradoxa (Fitzinger)

The four paired gill arches of the South American lungfish Lepidosiren paradoxa contain single branchial arteries directly connecting dorsal and ventral arteries. In gill arches 3 and 4 the branchial arteries also supply looped arlerioles and capillaries to much-reduced gill filaments. Regulation of blood between these routes is thought to be by alteration of vascular resistance. Within the filaments, extensive subepithelial capillary networks and numerous small pumps connect lymphatic vessels in the central connective tissue compartment with venules which, in turn, drain to paired branchial veins.
The features of the endothelium of many of the filament blood vessels suggest extensive transporting, haematolytic and granulopoeitic functions. Large numbers of macrophages pack the connective tissue. Many contain extensive quantities of haemosiderin.     

Stem anatomy of the dwarf subshrub Cressa cretica L. (Convolvulaceae)

Stem anatomy and development of medullary phloem are studied in the dwarf subshrub Cressa cretica L. (Convolvulaceae). The family Convolvulaceae is dominated by vines or woody climbers, which are characterized by the presence of successive cambia, medullary- and included phloem, internal cambium and presence of fibriform vessels. The main stems of the not winding C. cretica shows presence of medullary (internal) phloem, internal cambium and fibriform vessels, whereas successive cambia and included phloem are lacking. However, presence of fibriform vessels is an unique feature which so far has been reported only in climbing members of the family. Medullary phloem develops from peri-medullary cells after the initiation of secondary growth and completely occupies the pith region in fully grown mature plants. In young stems, the cortex is wide and formed of radial files of tightly packed small and large cells without intercellular air spaces. In thick stems, cortical cells become compressed due to the pressure developed by the radial expansion of secondary xylem, a feature actually common to halophytes. The stem diameter increases by the activity of a single ring of vascular cambium. The secondary xylem is composed of vessels (both wide and fibriform), fibres, axial parenchyma cells and uni-seriate rays. The secondary phloem consists of sieve elements, companion cells, axial and ray parenchyma cells. In consequence, Cressa shares anatomical characteristics of both climbing and non-climbing members. The structure of the secondary xylem is correlated with the habit and comparable with that of other climbing members of Convolvulaceae.     

Decreased fibrinolytic activity in porcine-to-primate cardiac xenotransplantation.

BACKGROUND: One major barrier to successful xenotransplantation is acute vascular rejection, a process pathologically characterized by microvascular thrombosis and diffuse fibrin deposition in transplant blood vessels. This pathologic picture may result from a disturbance in the coagulant or fibrinolytic pathways that regulate normal vascular patency. This study evaluated the regulation of fibrinolytic activity defined by tissue plasminogen activator and plasminogen activator inhibitor-1 as it may exist in the setting of acute vascular rejection. MATERIALS AND METHODS, RESULTS: Serial biopsies from cardiac xenotransplants evaluated by immunofluorescence microscopy demonstrated progressive decreases in tissue plasminogen activator and increases in plasminogen activator inhibitor-1. In vitro studies measuring fibrinolytic activity of cell culture medium from porcine aortic endothelial cells stimulated with human serum or autologous porcine serum revealed that human serum triggered as much as 93% increase in antifibrinolytic activity. CONCLUSIONS: These findings demonstrate that porcine vascular endothelial cells change toward an antifibrinolytic state following stimulation with human xenoreactive antibodies and complement. The shift is at least partly explained by an increased ratio of plasminogen activator inhibitor-1 to tissue plasminogen activator, and is at least in part mediated by the activation of complement. This increased antifibrinolytic activity may contribute to the thrombotic diathesis seen in acute vascular rejection in pig-to-primate xenografts.     

Development of the crystalline-array virus (CAV) in cultures of dorsal vessels from Schistocerca americana (Orthoptera: Acrididae)

Dorsal vessels of Schistocerca americana were maintained for 6 days in organ culture systems with a medium consisting of 60% M-18, 30% modified Grace's medium, and 10% fetal bovine serum. Homogenates of the dorsal vessels that were exposed to medium containing the crystalline-array virus (CAV) showed increased virus activity compared with the original inoculating medium at 6 days after exposure, and most adsorption occurred during the first hour of exposure. Further testing indicated that a major portion of increased virus activity occurred within 24 hr after infection which suggested that the viral particles were incorporated into crystals which were not dispersed when injected into the hemocoel of grasshoppers.     

Histomorphogenesis and immunohistochemical study of the bovine pineal gland (Bos taurus) during prenatal development (160 days of gestation to birth)

The ontogenesis of the pineal gland of 20 bovine embryos (Bos taurus) has been analysed from 160 days of gestation to birth by means of optical microscopy and immunohistochemical techniques. For this study, the specimens were grouped into two stage in accordance with the most relevant histological characteristics: Stage 1 (160 to 200 days of prenatal development) and Stage 2 (220 days of prenatal development to birth). At 160 days of gestation some rounded structures with a central lumen, which we refer to as glandular rosettes, begin differentiation from the epithelium of the pineal recess, experiencing an extraordinary increase in number and size at 200 days of intrauterine life. In the interior of the pineal parenchyma we observed some morphologically rounded cells with oval euchromatic nuclei and a well-differentiated nucleolus that we refer to as the pinealoblasts. We also observed other cells characterised by the presence of low cytoplasm and rounded and highly stained nuclei that we refer to as the interstitial cells. The glandular stroma is formed from the capsular, trabecular, and perivascular connective tissue as well as from the reticular network that comes from the cellular processes of the interstitial cells. The blood vessels, at 240 of gestation, show well-formed walls where the endothelial cells stand out. At 160 days of gestation we witnessed some cells with small, dense, oval nuclei, positive to the glial fibrillary acidic protein (GFAP). At this age NPY positive fibres were detected, distributed around the blood vessels and among the pinealoblasts. We conclude by clarifying that the changes detected in the morphology as well as in the number and size of glandular rosettes appear to be related to the functional activity of the pineal gland during embryonic development.     

Adenosine mediation of mesenteric blood flow.

The mesenteric circulation is regulated by multiple mechanisms, there is sufficient reason to support the suspicion that local metabolic factors are especially important in the control of intestinal vasculature. Of these, adenosine, a purine nucleoside and mesenteric vasodilator, may be the messenger of the intestinal tissue to signal appropriate responses of the intestinal vessels. The evidence supporting the candidacy of the nucleoside as a local regular of mesenteric circulation may be summarized, as follows: Adenoside is present in the tissue of the gut in measurable quantities. Exogenous adenosine is a powerful dilator of mesenteric resistance vessels. Blockade of adenosine receptors in the mesenteric circulation interferes significantly with three autoregulatory phenomena, i.e., postprandial hyperemia, pressure-flow autoregulation, and reactive hyperemia. The evidence which weakens the role of adenosine as mesenteric vasoregulator includes: Findings in several reports that adenosine depressed intestinal oxygen consumption. The failure of adenosine receptors to inhibit some autoregulatory hyperemias of the gut and the rather limited amount of evidence regarding tissue adenosine release in autoregulatory responses of the gut's vasculature.     

The effects of large blood vessels on temperature distributions during simulated hyperthermia.

Several three-dimensional vascular models have been developed to study the effects of adding equations for large blood vessels to the traditional bioheat transfer equation of Pennes when simulating tissue temperature distributions. These vascular models include "transiting" vessels, "supplying" arteries, and "draining" veins, for all of which the mean temperature of the blood in the vessels is calculated along their lengths. For the supplying arteries this spatially variable temperature is then used as the arterial temperature in the bioheat transfer equation. The different vascular models produce significantly different locations for both the maximum tumor and the maximum normal tissue temperatures for a given power deposition pattern. However, all of the vascular models predict essentially the same cold regions in the same locations in tumors: one set at the tumors' corners and another around the inlets of the large blood vessels to the tumor. Several different power deposition patterns have been simulated in an attempt to eliminate these cold regions; uniform power in the tumor, annular power in the tumor, preheating of the blood in the vessels while they are traversing the normal tissue, and an "optimal" power pattern which combines the best features of the above approaches. Although the calculations indicate that optimal power deposition patterns (which improve the temperature distributions) exist for all of the vascular models, none of the heating patterns studied eliminated all of the cold regions. Vasodilation in the normal tissue is also simulated to see its effects on the temperature fields.(ABSTRACT TRUNCATED AT 250 WORDS)