Investigation of the putative relationship of molecules which playing a role in the angiogenesis with C-TYPE natriuretic peptide by using the chicken embryo chorioallantoic membrane model

The chick chorioallantoic membrane (CAM) is a widely used model to follow the developmental processes in angiogenesis studies. This thesis study aims to describe the putative involvement of CNP-3, the chick homolog of human CNP, and its receptor natriuretic peptide receptor (NPR)-B besides known angiogenic factors and their receptors, vascular endothelial growth factor (VEGF)-A/ vascular endothelial growth factor receptor (VEGFR)-2 and fibroblast growth factor (FGF)-2/fibroblast growth factor receptor (FGFR)-2, in angiogenesis of the CAM. CAM samples between developmental days E7 and E20 were collected for light microscopic and transmission electron microscopic analyses. Expression of CNP-3/NPR-B, VEGF-A/VEGR-2, FGF-2/FGFR-2 mRNA in these CAM samples were also studied between E7 and E20. Light microscopy and electron microscopy analyzes showed that, vascular organization was mostly within the chorionic mesenchyme as endothelial tube-like structures on E7-E8 days. On E9 and later, advanced blood vessels were observed within the mesenchyme. VEGF-A and FGF-2 expression were observed in the early stages of CAM development (E7-E9) with a peak at E8. These molecules showed a second peak at around E16. Co- expression of VEGF-A, FGF-2 and CNP-3 were seen at E16-E20. VEGFR-2 expression was observed between E7-E12, whereas expression of FGFR-2 showed its first peak between E7-E9 and its second peak between E16-20. NPR-B expression, on the other hand, was observed between E7-E20 with its highest level at E16. In conclusion, the results revealed that CNP-3 may have a role in vascular organization via its NPR-B receptor in the later stages, i.e., E16-E20, of CAM development.