The modality of transendothelial passage of lymphocytes and tumor cells in the absorbing lymphatic vessel.

The modality of transendothelial passage of the macromolecules and cells (lymphocyte and cancer cells) in the absorbing lymphatic vessel (ALV) and the tumor-associated absorbing lymphatic (TAAL) vessel is studied. On the basis of the peculiar plasticity of the lymphatic endothelial cell of these vessels (lacking a continuous basement membrane, pores and open junctions) the endothelial wall organizes formation of the intraendothelial channel, by means of molecular interactions as yet unidentified. The remarkable finding of the intravasation of lymphocyte and experimental tumor cancer cells (T84 colon Adenocarcinoma, B16 melanoma in nude mice and spontaneous prostate adenocarcinoma in trans-genic mice) should be stressed. This intravasation takes place, under both physiologic and pathological conditions, following the same transendothelial morphological modality, i.e. the intraendothelial channel - a dynamic and transient entity - is probably also induced by similar molecular interactions, a crucial point that merits future research.