1,721,475 research outputs found
Nicole Le Douarin and the use of quail-chick chimeras to study the developmental fate of neural crest and hematopoietic cells
Full text linkThe quail-chick chimera marking system, devised in 1969, gave a new impetus to the analysis of cell migrations and interactions in the developing nervous, immune and hematopoietic systems. The method is based on the observation that the constitutive heterochromatin in all embryonic and adult cells of the quail is condensed in one large mass in the centre of the nucleus and is associated with the nucleolus, making this organelle strongly stained with the Feulgen–Rossenbeck reaction. The association of cells or rudiments from two avian species, advocated as a means to identify cells that migrate during embryogenesis, was rapidly recognized in this context as a useful tool for the study of many developmental biology problems. This article summarizes the fundamental contribution of Nicole Le Douarin to the discovery and the application of this technique over the last 40 years
The discovery of the fundamental role of VEGF in the development of the vascular system
Full text linkIn the 1980', vascular endothelial growth factor (VEGF), also known as vascular permeability factor (VPF) was identified and shown to be a key regulator of endothelial cell proliferation and migration, and vascular permeability. The essential role of VEGF and of VEGF receptors (VEGFRs) for the development of the embryonic vascular system has been established via gene disruption studies. This article summarizes the fundamental contributions that have been made in the early days of angiogenesis research to define the involvement of VEGF/VEGFRs in the developing vasculature
From horror autotoxicus to autoimmunity. An historical note
No full textAt the beginning of the 20th century, the knowledge on autoimmunity was very limited. In 1899, Jules Bordet demonstrated that autoantibodies specific for erythrocytes could cause their own destruction in conjunction with serum complement. In 1904, Julius Donath and Karl Landsteiner reported the first observation of a true autoimmune disease, paroxysmal cold hemoglobinuria, a complement-dependent hemolytic anemia. They demonstrated the presence of a lytic substance in the blood of three patients with paroxysmal cold hemoglobinuria. An autoimmune disease can generally be defined as one in which an autoantibody or a sensitized lymphocyte reacts with host tissue. The prevalence of autoimmune diseases is significantly increasing in the world population. We now recognize more than 80 clinically distinct human diseases that result at least in part from an autoimmune response. Autoimmune diseases generally result from the association of genetic susceptibility and environmental triggers. Infectious agents have long been the most well-studied environmental factors. Despite the diversity in natural history and presentation, autoimmune diseases share a number of underlying mechanisms. More selective and less toxic immunosuppressive and immunomodulatory agents are used to treat these disorders, and promising immune tolerance approaches are emerging
Corticosteroids and cerebral vessel permeability during embryonic development
No full textThe effects of cortisol on the development of the blood-brain barrier (b.b.b.) were microscopically investigated in the chick embryo optic tectum using horseradish peroxidase (hrp) as marker of vascular permeability. Hrp was injected intracardially at the 15th and 21st incubation day (i.d.), i.e. 5 and 11 days after the last administration of the drug (10 micrograms/50 microliters saline solution at the 8th and 10th i.d.). This treatment caused damage to the maturation process of the b.b.b. to hrp. The intraneural blood vessel walls were not able to prevent the marker extravasation which was massive at the 15th i.d. and circumscribed to limited perivascular areas at the 21st i.d. A possible pathogenetic mechanism of this phenomenon is discussed
Spatial Statistics-Based Image Analysis Methods for the Study of Vascular Morphogenesis
No full textSeveral studies are available addressing the mechanisms of vascular morphogenesis in order to unravel how cooperative cell behavior can follow from the underlying, genetically regulated behavior of endothelial cells and from cell-to-cell and cell-to-extracellular matrix interactions. From the morphological standpoint several aspects of the process are of interest. They include the way the pattern of vessels fills the available tissue space and how the network grows during the angiogenic process, namely how a main trunk divides into smaller branches, and how branching occurs at different distances from the root point of a vascular tree. A third morphological aspect of interest concerns the spatial relationship between vessels and tissue cells able to secrete factors modulating endothelial cells self-organization, thus influencing vascular rearrangement. In the present chapter image analysis methods allowing for a quantitative characterization of these morphological aspects will be detailed and discussed. They are almost based on concepts derived from the theoretical framework represented by spatial statistics
Vascular Morphogenesis: Methods and Protocols
No full textVascular Morphogenesis: Methods and Protocols provides a range of techniques for studying vascular morphogenesis in vivo and in vitro, reflecting advances in the field. Endothelial cell signaling is currently believed to promote fundamental cues for cell fate specification, embryo patterning, organ differentiation and postnatal tissue remodeling. Understanding the concept of vascular bed specificity represents a major challenge for future investigations. Indeed, one of the most interesting theoretical perspectives and practical applications of endothelial cell signaling is the possibility for these cells to maintain their inductive potential during adult life. Written in the highly successful Methods in Molecular Biology series format, chapters include introductions to their respective topics, lists of the necessary materials, step-by-step, readily reproducible laboratory protocols and tips on troubleshooting and avoiding known pitfalls.
Practical and authoritative, Vascular Morphogenesis: Methods and Protocols will serve as a instructive and useful reference for cell biologists, anatomists, pathologists and physiologists, as well as all those interested in this area of biological stud
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