The organisation of the stromal cell compartment in the mouse
lymph node was studied by light and electron microscopy after tissue
impregnation by the zinc iodide-osmium (ZIO) method. Fibroblastic
reticular cells (FRCs) represented the main stromal cell population.
These cells were located both in the cortical region and in the medulla
and exhibited various configurations. In the cortex, FRCs were
fusiform in shape and came into close proximity with the floor of the
subcapsular sinus. In the medulla, the FRCs were shaped like irregular
dendritic cells which formed a complex 3-dimensional network. The FRCs
surrounded vascular structures such as capillaries and/or high
endothelial venules; in these instances they were organised in a
discontinuous sheath-like fashion around the vessel wall. By light and
electron microscopy, FRCs have been observed to come in close spatial
relationship with a number of cells in the lymph node, including sinus
endothelial cells, the endothelium of high endothelial venules and
capillaries, various types of lymphocytes, follicular dendritic cells
and interdigitating cells. These microanatomical features are
consistent with the proposal that FRCs may be involved in the
communicative networks between the different lymph node compartments.
In particular, the FRCs may be involved in the transport of molecules
from the sinus compartment to the high endothelial venules or to the
distinct cell populations in the lymphoid parenchyma.