How do cells get from the bone marrow into peripheral circulation?
a. Stem cells escape the bone marrow and mature in peripheral circulation.
b. Mature cells attach to a carrier protein for transport.
c. Capillaries flow into the marrow and pluck out precursor cells.
d. Mature cells squeeze through spaces in the vessel endothelial lining.
ANS: D
As mature blood cells come into contact with endothelial cells in the bone marrow, they bind to the surface via a receptor-mediated process. The binding creates a space between the luminal adventitial and endothelial cells. This allows the bone marrow cells to escape into circulation.
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