Ultrastructural localization of elastin-like immunoreactivity in the extracellular matrix around human small lymphatic vessels

The distribution of elastin-like immunoreactivity around small lymphatic vessels wasinvestigated in three different human tissues (skin, heart and dental pulp) using high resolutionimmunocytochemistry. Quantitative assessment of the immunogold reaction was performed withan image analysis system. Intense and moderate elastin-immunoreactivity was detected in theextracellular matrix around small lymphatic vessels of the skin and heart, respectively. Bycontrast, absence of immunostaining was observed around lymphatic vessels in the dental pulp.Although the staining was mostly detectable on the non-fibrillar amorphous component of theextracellular matrix, some microfibrils were also immunostained in close proximity to thelymphatic vessel wall. These findings support the concept that small lymphatic vessels may beheterogeneous with respect to the composition of the extracellular matrix around their wall. Theobservation that it is possible to observe small lymphatic vessels displaying low or no elastinimmunoreactivity in the adjoining matrix militates against the hypothesis that elastic fibers playa pivotal role in the mechanisms that regulate the function of small lymphatic vessels.