chapter 27 Development of cirCulatory systen
Chapter 27 Development of circulatory system
1 Formation of primitive cardiovascular system
1. Formation of primitive cardiovascular system
1) extra-embryonic blood vessels ---blood island at the middle of 3rd week, wall of the yolk sac mesenchyma proliferate and/ form isolated cell clusters, the peripheral cell become flattened and differentiate into endothelial cell to from endothelial tube central located cells are detached and develop into primitive blood cells(blood stem cell 血岛
1) extra-embryonic blood vessels ---blood island: at the middle of 3 rd week, wall of the yolk sac mesenchyma proliferate and form isolated cell clusters, the peripheral cell become flattened and differentiate into endothelial cell to from endothelial tube; central located cells are detached and develop into primitive blood cells(blood stem cell)
-endothelial tube approach and fuse with each other to form an endothelial tube network endothelial tube network appears in chorionic membrane and body stalk, and connect to vitelline circulation 原始血管 原始血细胞
---endothelial tube approach and fuse with each other to form an endothelial tube network ---endothelial tube network appears in chorionic membrane and body stalk, and connect to vitelline circulation
2)intra-embryonic blood vessels by the 18-20th days, endothelial tube network appears in intraembryonic mesenchyma to form intraembryonic endothelial tube network by the end of 3rd week, intraembryonic and extraembryonic endothelial tube networks connect to each other to form a diffuse endothelial tube network c-endothelial tube networks fuse or disappear to form primitive cardiovascular system
2) intra-embryonic blood vessels ---by the 18-20th days, endothelial tube network appears in intraembryonic mesenchyma to form intraembryonic endothelial tube network ---by the end of 3 rd week, intraembryonic and extraembryonic endothelial tube networks connect to each other to form a diffuse endothelial tube network ---endothelial tube networks fuse or disappear to form primitive cardiovascular system