We have reviewed physiological significance of rhythmical spontaneous contractions of collecting lymphatics, which play an important role in lymph transport and seem to regulate lymph formation through changing the pacemaker sites of the rhythmic contractions and conractile patterns of lymphangions. Next, we reported experimental findings that the wall effective permeability of hydrophilic substances labelled with fluorescent dyes was evaluated in an isolated cannulated rat single lymphatic using a microscope system. With the experimental evidence, we have discussed physiological significance and crucial roles of the enrichment of albumin in lymph through the wall of small lymphatics in regulation of innate immunity. In addition, we have described the mode of action of recanalization of collecting lymphatics after excision of lymph node with special reference to clinical treatment for surgical removal of lymph nodes-mediated secondary lymphedema. Finally, we have addressed the possibility that primary tumor cells and/or metastatic carcinoma cells themselves release key chemical substances to develop environment suitable for micro-metastasis in sentinel lymph node.
Keywords: Spontaneous contraction, active lymph transport, enrichment of albumin, innate immunity, recanalization, lymphatic endothelial cell, micrometastasis, sentinel lymph node