Library · Histology
High endothelial venule
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Lymphocytes, the defense cells that travel in the blood, do not enter lymphoid tissue just anywhere. Naive T lymphocytes, the ones that have not yet met their antigen, cross the wall of specialized venules: the high endothelial venules. A venule is a very small vessel that collects blood from the capillaries.
Inside the lymph node, those venules supply most of the lymphocytes. The lymphocytes cross by diapedesis, the passage of a cell between the cells of the vessel wall, with the help of adhesion molecules on the endothelium, the inner lining of the vessel. It is a doorway in the wall of a vessel.
Through it pass naive B and T lymphocytes, two families of those defense cells that have not yet met their antigen, the molecule each one recognizes.
The recognition is molecular. Naive T lymphocytes carry a protein on their surface, L-selectin, which recognizes vascular addressins such as CD34 and GlyCAM-1, molecules that in lymph nodes are expressed precisely on the high endothelial venules.
In brief
Naive T lymphocytes enter lymphoid tissue by crossing the wall of specialized venules, the high endothelial venules.
In the lymph node they supply most of the lymphocytes, which enter by diapedesis thanks to adhesion molecules on the endothelium.
An access door open in the wall of a vessel.
They let through naive B and T lymphocytes, the ones that have not yet met their antigen.
L-selectin on naive T lymphocytes recognizes vascular addressins such as CD34 and GlyCAM-1, which in lymph nodes are expressed on those venules.
Sources (2)
- Immunobiology: The Immune System in Health and Disease, 5th edition, Garland Science, NCBI BookshelfLymphocyte migration, activation and effector function, ImmunobiologyPublished
- National Center for Biotechnology Information, StatPearls PublishingAnatomy, Lymph Nodes, StatPearlsPublished
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