Mast cells are present during angiogenesis in the chick extraembryonic vascular system

The extraembryonic vascular membranes of 3-day-18-day chick embryos were examined for the presence of mast cells. As early as 3.5 days mast cells were found on the area vasculosa. It is suggested that these cells have a role in angiogenesis of the chick extraembryonic vascular system.     

Lipid droplets of neuroepithelial cells are a major calcium storage site during neural tube formation in chick and mouse embryos

In situ precipitation of calcium (Ca²⁺) with fluoride and antimonate shows that Ca²⁺-specific precipitate is localized almost exclusively within lipid droplets of neuroepithelial cells during neural tube formation in chick and mouse embryos. The density of Ca²⁺ precipitate within lipid droplets is generally greater in the apical ends of cells situated in regions of the neuroepithelium that are actively engaged in bending. These findings suggest that lipid droplets, in addition to providing a source of metabolic fuel for developing neuroepithelial cells, also serve as Ca²⁺-storage and-releasing sites during neurulation.This study was supported by grants from the NIH (NS23200), the BRSG fund of UMDNJ, and the Busch Fund of Rutgers University. Dr Bush was supported by a New Jersey State Postdoctoral Fellowship.     

Short axon ganglion cells in the chick retina

Using Golgi's staining technique, we investigated some ganglion cells whose axons do not project out of the retina area. These axons, after following a short trajectory through the optic nerve fiber layer or through the 5th stratum of the inner plexiform layer (IPL), change their direction and end in the inner stratum of the IPL.     

Short axon ganglion cells in the chick retina

Summary Using Golgi's staining technique, we investigated some ganglion cells whose axons do not project out of the retina area. These axons, after following a short trajectory through the optic nerve fiber layer or through the 5th stratum of the inner plexiform layer (IPL), change their direction and end in the inner stratum of the IPL.     

Mast cells,co-carcinogenesis and anti-carcinogenesis in the skin of mice

Zusammenfassung Wenn auf der Haut der Maus eine Karzinogenese mit minimalen Dosen eines reinen Initiators und eines reinen Promoters (Co-karzinogen) induziert wird, tritt eine Mastzellreaktion auf. Diese Reaktion erreicht ein Maximum unter den Papillomen. Sie kann durch Applikation eines Antikarzinogens verhindert werden.     

Mast cells stimulated by membrane-bound,but not soluble,steel factor are dependent on phospholipase C activation

The steel factor (SLF) and c-Kit growth factor/receptor pair are key molecules governing mast cell development and survival. SLF is expressed on stromal cells as a membrane-bound molecule (mSLF) which can be cleaved by proteases to release a soluble form (sSLF). We investigated the importance of phospholipase C (PLC) activation in mast cells stimulated by sSLF and mSLF. PLC antagonists U73122, neomycin sulfate and oleic acid inhibited mast cell thymidine incorporation stimulated by mSLF, but not by sSLF. These antagonists suppressed sSLF-induced Ca2+ transients but did not significantly interfere with c-Kit phosphorylation or PLC-gamma2 recruitment. p85, the regulatory subunit of phosphatidylinositol 3-kinase (PI3-kinase), was found to be efficiently recruited to c-Kit following stimulation by sSLF or mSLF. However PKB/Akt, a kinase activated by PI3-kinase products, was phosphorylated following sSLF stimulation, but not with mSLF. Taken together, these studies demonstrate the importance of PLC activation by mSLF in supporting mast cells.     

Developmental and pathological angiogenesis in the central nervous system

Angiogenesis, the formation of new blood vessels from pre-existing vessels, in the central nervous system (CNS) is seen both as a normal physiological response as well as a pathological step in disease progression. Formation of the blood–brain barrier (BBB) is an essential step in physiological CNS angiogenesis. The BBB is regulated by a neurovascular unit (NVU) consisting of endothelial and perivascular cells as well as vascular astrocytes. The NVU plays a critical role in preventing entry of neurotoxic substances and regulation of blood flow in the CNS. In recent years, research on numerous acquired and hereditary disorders of the CNS has increasingly emphasized the role of angiogenesis in disease pathophysiology. Here, we discuss molecular mechanisms of CNS angiogenesis during embryogenesis as well as various pathological states including brain tumor formation, ischemic stroke, arteriovenous malformations, and neurodegenerative diseases.     

Primary asymmetry in the distribution of primordial germ cells during colonization of gonadal buds in chick embryo]

Analysis of the numerical data obtained from a population of 529 chick embryos, selected according to their stage of development, shows that the primary distribution of PGC is asymmetric with a bias towards the left side. The kinetics of the colonisation process are in conformity with the law of logistic growth: the number of PGC settling in the germinal epithelia tends to an upper limit not exceeding the number of PGC identifiable in the anterior germinal crescent. Taking the embryo population as a whole, the degree of primary asymmetry at the end of colonisation is such that 56% of the total number PGC fixed in the gonadial primordia are found in the left epithelia.     

Mast cells in the skin of normal,hairless and athymic mice

Summary The skin of congenitally athymicnu/nu mice is rich in mast cells which stain metachromatically, contain histamine and 5-hydroxytryptamine, and participate in the PCA reaction. Mast cells of athymic mice have thus the attributes of normal mast cells.This work was supported by grants from the Swiss National Science Foundation (No. 3.516.71 and 3.234.74) and the Fritz Hoffmann-La-Roche-Stiftung.The skilful technical assistance of MissR. Keist is gratefully acknowledged.     

Mast cell reaction during chemical skin carcinogenesis of the lizardLacerta agilis

Zusammenfassung Beschreibung der Mastzellenreaktion während der chemisch-induzierten Carcinogenese bei der EidechseLacerta agilis.     

Mast cells and hibernation: Observations in the Indiana bat,Myotis sodalis

Zusammenfassung Untersuchungen über die Zahl der Mastzellen und den Histamingehalt in Gewebe der Indiana-FledermausMyotis sodalis während des Winterschlafes zeigten keine Unterschiede zwischen den im Herbst, Winter und Frühling getöteten Tieren.     

Role of plasminogen activator-plasmin system in tumor angiogenesis

New blood formation or angiogenesis has become a key target in therapeutic strategies aimed at inhibiting tumor growth and other diseases associated with neovascularization. Angiogenesis is associated with important extracellular remodeling involving different proteolytic systems among which the plasminogen system plays an essential role. It belongs to the large serine proteinase family and can act directly or indirectly by activating matrix metalloproteinases or by liberating growth factors and cytokines sequestered within the extracellular matrix. Migration of endothelial cells is associated with significant upregulation of proteolysis and, conversely, immunoneutralization or chemical inhibition of the system reduces angiogenesis in vitro. On the other hand, genetically altered mice developed normally without overt vascular anomalies indicating the possibility of compensation by other proteases in vivo. Nevertheless, they have in some experimental settings revealed unanticipated roles for previously characterized proteinases or their inhibitors. In this review, the complex mechanisms of action of the serine proteases in pathological angiogenesis are summarized alongside possible therapeutic applications.     

The expression levels of three raft-associated molecules in cultivated vascular cells are dependent on culture conditions

Relaying a signal across the plasma membrane requires functional connections between the partner molecules. Membrane microdomains or lipid rafts provide an environment in which such specific interactions can take place. The integrity of these sites is often taken for granted when signalling pathways are investigated in cell culture. However, it is well known that smooth muscle and endothelial cells undergo cytoskeletal rearrangements during monolayer culturing. Likewise affected – and with potentially important consequences for signalling events – is the organization of the plasma membrane. The expression levels of three raft markers were massively upregulated, and raft-associated 5-nucleotidase activity increased in conventional monolayer cultures as compared with a spheroidal coculture model, shown to promote the differentiation of endothelial cells. Our data point to a shift of raft components in monolayer cultures and demonstrate potential advantages of the spheroid coculture system for investigation of raft-mediated signalling events in endothelial cells.Received 4 August 2003; received after revision 18 September 2003; accepted 25 September 2003     

Differentiation of chick embryo brain cells in culture

Résumé Des cellules, encore à un stade indifférencié, dissociées d'hémisphères cérébraux d'embryon de Poulet ont formé, en culture, des fibres nerveuses. La plupart des cellules se différencient en neuroblastes unipolaire et bipolaire; certaines évoluent vers le type multipolaire sans contact direct avec des cellules gliales.

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