This section from the esophagus shows a capillary cut in longitudinal section
and containing erythrocytes. Note the flattened
nuclei of the endothelial
cells that form the wall of this vessel. No other covering is apparent,
although capillaries have a thin covering of collagen fibers derived from
the surrounding connective tissue. Note that the diameter of the capillary
is the same as the diameter of the erythrocytes. The irregular, cell-lined
spaces below the capillary, which do not contain blood cells, are
lymph capillaries.
