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Plasticité et formation des artères et des veines dans l'oeuf de Poulet. Auteur : Delphine Moyon (INSERM U36, Collège de France) Table des matières 1.

Plasticité et formation des artères et des veines dans l'oeuf de Poulet

Introduction Le système sanguin des Vertébrés est composé de trois éléments : un liquide (le sang), une pompe (le coeur) qui permet de mettre ce liquide en mouvement, et des conduits (les vaisseaux). On distingue trois types de conduits, les artères, les veines et les capillaires, qui diffèrent aussi bien par leur fonction que par leur structure. Artères et veines forment un réseau continu de vaisseaux sanguins, reliées par les capillaires et le coeur. Grâce aux techniques de biologie moléculaire, il est maintenant possible d'étudier la formation des artères et des veines aussi bien du point de vue des molécules présentes à la surface des vaisseaux que du point de vue de leur morphologie. 2. Au cours du développement embryonnaire, veines et artères se mettent en place progressivement à partir d'un plexus capillaire (une sorte de maillage de petits vaisseaux). Les kératines : un autre regard sur la biologie de la peau.

Holbrook KA, Wolff K.

Les kératines : un autre regard sur la biologie de la peau

The structure and development of skin. In: Fitzpatrick TB, et al., eds. Dermatology in general medicine. New York: McGraw-Hill, 1993 : 97–144. Fuchs E, Byrne C. Steinert PM. Fuchs E. Carnegie Stage 1-1 – Schematic of events of fertilization of stage 1a and 1b embryos. A.

Carnegie Stage 1-1 – Schematic of events of fertilization of stage 1a and 1b embryos

Sperm-oocyte membrane fusion and sperm incorporation into the oocyte cytoplasm. B. Cortical and zonal reactions composed of exocytosis of cortical granules and interaction of their contents with the zona pellucida, respectively;. C. Extrusion of the second polar body, completing second maturation. D. CR = cortical reactionFC = fertilization coneFPn = female pronucleusIb = interbodyMPn = male pronucleusPB1 = first polar bodyPB2 = second polar bodySS = subzonal spaceS = sperm headSp = maturation spindleZ = zonal pellucidaZR = zonal reaction From: Sathananthan et al., 1986. Keywords: cortical reaction, female pronucleus, fertilization cone, first polar body, interbody, male pronucleus, maturation spindle, second polar body, sperm head, subzonal space, zona pellucida, zonal reaction Source: The Virtual Human Embryo.

Department of Botany. Galerie Web Photo Adobe. Untitled Document. Chordin forms a self-organizing morphogen gradient in the extracellular space between ectoderm and mesoderm in the Xenopus embryo Jean-Louis Plouhinec, Lise Zakin, Yuki Moriyama and E.

Untitled Document

M. De Robertis The vertebrate body plan follows a stereotypical dorsal-ventral (D-V) tissue differentiation controlled by Bone Morphogenetic proteins (BMP) and secreted BMP antagonists such as Chordin. The three germ layers – ectoderm, mesoderm and endoderm – are affected coordinately by the Chordin/BMP morphogen system. Complexity and Analogy in Science Pontifical Academy of Sciences, Acta 22, Vatican City 2014 www.pas.va/content/dam/accademia/pdf/acta22/acta22-derobertis.pdf Edward M. Introduction One of the most complex and mysterious processes in nature is the development of a vertebrate animal from a single cell into an organism consisting of hundreds of differentiated cell types that are reproducibly arranged in specific spatial patterns. 1 Living organisms are shaped by their evolutionary history.

Gastrulation: From Cells To Embryo. Biologie du développement II. Exploring the mechanism of action of the sperm-triggered calcium-wave pacemaker in ascidian zygotes. BCPST SUPC2. Sperm Proteasomes Degrade Sperm Receptor on the Egg Zona Pellucida during Mammalian Fertilization. Abstract Despite decades of research, the mechanism by which the fertilizing spermatozoon penetrates the mammalian vitelline membrane, the zona pellucida (ZP) remains one of the unexplained fundamental events of human/mammalian development.

Sperm Proteasomes Degrade Sperm Receptor on the Egg Zona Pellucida during Mammalian Fertilization

Evidence has been accumulating in support of the 26S proteasome as a candidate for echinoderm, ascidian and mammalian egg coat lysin. Monitoring ZP protein degradation by sperm during fertilization is nearly impossible because those few spermatozoa that penetrate the ZP leave behind a virtually untraceable residue of degraded proteins. We have overcome this hurdle by designing an experimentally consistent in vitro system in which live boar spermatozoa are co-incubated with ZP-proteins (ZPP) solubilized from porcine oocytes.

Using this assay, mimicking sperm-egg interactions, we demonstrate that the sperm-borne proteasomes can degrade the sperm receptor protein ZPC. Received: July 28, 2010; Accepted: January 27, 2011; Published: February 23, 2011.