Tie2 expression in human embryonic tissues.

Tie2 is a member of receptor tyrosine kinases family, involved in vasculogenesis and angiogenesis. Its main role is to stabilize, maintain, and facilitate the structural adaptation of the vasculature, during embryo development, and adult wound healing, or tumor development. Tissues from human embryos found in different stages of development (5 and 7-week-old), were investigated for Tie2 expression. The reaction was positive, with maximum intensity in the vascular cords, found in the mesenchymal tissue, and in the connective tissue around the primitive spinal cord. In the 7-week-old embryo, the reaction was negative in large blood vessels, and it was heterogeneous in those showing bridging phenomenon. In conclusion, during the first two months of human embryo development, we have concurrent vasculogenesis, angiogenesis, and blood vessel maturation and stabilization.