text: Chicken CCN3 expression in embryonic and extraembryonic tissues
  Expression of CCN3 in axial structure becomes visible in the presegmentation stage and reaches to the highest level at the beginning of somitogenesis (HH stage 7, Fig. 1a). Strong similarity between CCN3 and Sonic Hedgehog was observed for the expression pattern in axial structure (notochord and floor plate), in which the left-right asymmetrical pattern in the node area is also conserved (Fig. 1b). However, Sonic Hedgehog expression is slightly broader than that of CCN3. Since CCN3 stimulates Notch signaling (Sakamoto et al. 2002), we investigated the expression of Notch signal genes. Among them, Serrate1, a ligand of Notch is unique because its expression is apparently a right deviated pattern in the node area (Fig. 1c). Another Notch ligand, Delta1 shows a right deviated pattern, but is more caudal area of the node extending to the primitive streak (data not shown). The expression of CCN3 in axial structure was followed by the presomitic mesoderm although it is diminished (Sakamoto et al. 2002). 
  Fig. 1
  Expression of mRNA in early stage chicken embryo; CCN3 (a), Sonic Hedgehog (b) and Serrate1 (c) at the beginning stage of somitogenesis (Hamburger and Hamilton (HH) Stage 7). Arrowheads indicate Hensen's node. Demonstrates the schematic view of tissue organization at this stage (d). Expression of CCN3 mRNA in blood islands of chicken extraembryonic tissue (HH stage 10) (e). Ventral part of the endothelial precursor cells in blood islands is positive for CCN3 expression. Coloration was stopped before the background staining started in sense probes (negative control)
  There is accumulating evidence of CCN3 commitment to hematopoiesis and therefore we investigated the CCN3 expression in extraembryonic tissues. Blood islands are formed in the yolk sac mesodermal area just between the visceral endodermal and ectodermal layers, which supply the red blood cells at the primary stage. The cells in blood islands are called hemangioblasts since they also differentiate into the endothelial cells of extraembryonic blood vessel structure. In chicken embryo, differentiating endothelial cells in the ventral part of blood islands express CCN3 from the initial stage (Fig. 1e). Erythroblasts in the center of blood islands (spherical cells in Fig. 1e) weakly express CCN3 and their expression is mildly enhanced in later stage (data not shown).
  
entities.text: ['embryonic']
entities.type: Tissue
entities.entity_id: PMC-2721088-sec-10_T1
entities.text: ['extraembryonic tissues']
entities.type: Tissue
entities.entity_id: PMC-2721088-sec-10_T2
entities.text: ['embryo']
entities.type: Developing_anatomical_structure
entities.entity_id: PMC-2721088-sec-10_T3
entities.text: ['tissue']
entities.type: Tissue
entities.entity_id: PMC-2721088-sec-10_T4
entities.text: ['extraembryonic tissue']
entities.type: Tissue
entities.entity_id: PMC-2721088-sec-10_T6
entities.text: ['endothelial precursor cells']
entities.type: Cell
entities.entity_id: PMC-2721088-sec-10_T7
entities.text: ['blood islands']
entities.type: Organism_substance
entities.entity_id: PMC-2721088-sec-10_T8
entities.text: ['blood islands']
entities.type: Organism_substance
entities.entity_id: PMC-2721088-sec-10_T5
entities.text: ['extraembryonic tissues']
entities.type: Tissue
entities.entity_id: PMC-2721088-sec-10_T9
entities.text: ['Blood islands']
entities.type: Organism_substance
entities.entity_id: PMC-2721088-sec-10_T10
entities.text: ['yolk sac mesodermal']
entities.type: Tissue
entities.entity_id: PMC-2721088-sec-10_T11
entities.text: ['visceral endodermal']
entities.type: Tissue
entities.entity_id: PMC-2721088-sec-10_T12
entities.text: ['ectodermal layers']
entities.type: Tissue
entities.entity_id: PMC-2721088-sec-10_T13
entities.text: ['red blood cells']
entities.type: Cell
entities.entity_id: PMC-2721088-sec-10_T14
entities.text: ['cells']
entities.type: Cell
entities.entity_id: PMC-2721088-sec-10_T15
entities.text: ['blood islands']
entities.type: Organism_substance
entities.entity_id: PMC-2721088-sec-10_T16
entities.text: ['hemangioblasts']
entities.type: Cell
entities.entity_id: PMC-2721088-sec-10_T17
entities.text: ['endothelial cells']
entities.type: Cell
entities.entity_id: PMC-2721088-sec-10_T18
entities.text: ['extraembryonic blood vessel structure']
entities.type: Developing_anatomical_structure
entities.entity_id: PMC-2721088-sec-10_T19
entities.text: ['embryo']
entities.type: Developing_anatomical_structure
entities.entity_id: PMC-2721088-sec-10_T20
entities.text: ['endothelial cells']
entities.type: Cell
entities.entity_id: PMC-2721088-sec-10_T21
entities.text: ['blood islands']
entities.type: Organism_substance
entities.entity_id: PMC-2721088-sec-10_T22
entities.text: ['Erythroblasts']
entities.type: Cell
entities.entity_id: PMC-2721088-sec-10_T23
entities.text: ['blood islands']
entities.type: Organism_substance
entities.entity_id: PMC-2721088-sec-10_T24
entities.text: ['cells']
entities.type: Cell
entities.entity_id: PMC-2721088-sec-10_T25
entities.text: ['ventral']
entities.type: Multi-tissue_structure
entities.entity_id: PMC-2721088-sec-10_T26
entities.text: ['Ventral']
entities.type: Multi-tissue_structure
entities.entity_id: PMC-2721088-sec-10_T27