THE MIGRATION OF LYMPHOCYTES ACROSS THE VASCULAR ENDOTHELIUM IN LYMPH NODES: A SCANNING ELECTRON MICROSCOPIC STUDY

M Nishi, N Hamada, H Nomura, M Mastueda, T Aiko

Abstract


Endothelial cells of Postcapillary Venules (PCV)
and the passage of lymphocytes through the wall
of PCV were investigated with Scanning Electron
Microscope (SEM) in mesenteric lymph nodes of
rats. Individual endothelial cells of PCV in the
lymph node did not have flat surface or were not
typically cubic, but swelled at the central part
assuming a foot ball-like shape. Circulating lymphocytes
are considered to migrate into lymphatic
tissues through the wall of PCV from the blood
stream. Two hypotheses, inter-endothelial cell
passage and intra-end othelial cell passage, have
been proposed. The three-dimensional studies on
lymphocytes passing the wall with SEM confirmed
that migrating lymphocytes pushes their way through
the intercellular space with pressing the adjoining endothelial
cells from beginning to end, supporting the
former hypothesis. Invasion of lymphocytes in to
endothelial cells were not observed.


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