Blood islands are structures in the developing embryo which lead to many different parts of the circulatory system.
They primarily derive from plexuses formed from angioblasts. Within them, vacuoles appear through liquefaction of the central part of the syncytium into plasma. The lumen of the blood vessels thus formed is probably intracellular. The flattened cells at the periphery form the endothelium.
The nucleated red blood corpuscles develop either from small masses of the original angioblast left attached to the inner wall of the lumen or directly from the flat endothelial cells. In either case the syncytial mass thus formed projects from and is attached to the wall of the vessel. Such a mass is known as a blood island and hemoglobin gradually accumulates within it. Later the cells on the surface round up, giving the mass a mulberry-like appearance. Then the red blood cells break loose and are carried away in the plasma. Such free blood cells continue to divide.
Blood islands have been seen in the area vasculosa in the omphalomesenteric vein and arteries, and in the dorsal aorta.
Famous quotes containing the words blood and/or island:
“If I’ve killed one man, I’ve killed two—
The vampire who said he was you
And drank my blood for a year,
Seven years, if you want to know.”
—Sylvia Plath (1932–1963)
“We crossed a deep and wide bay which makes eastward north of Kineo, leaving an island on our left, and keeping to the eastern side of the lake. This way or that led to some Tomhegan or Socatarian stream, up which the Indian had hunted, and whither I longed to go. The last name, however, had a bogus sound, too much like sectarian for me, as if a missionary had tampered with it; but I knew that the Indians were very liberal. I think I should have inclined to the Tomhegan first.”
—Henry David Thoreau (1817–1862)