LYMPH AN INTERSTITIAL FLUID-DYNAMICS IN LABIAL GINGIVAL TISSUES OF SHEEP

Lymphatic drainage and circulation in periodontal tissues have been ci ted as important components of host defence and pathogenic mechanisms, but quantitative data are sparse because of the technical difficultie s associated with small animal lymphatic studies. However, the lymphat ic vessels draining the periodontal tissues and surrounding region are sufficiently large in sheep to permit surgical placement of lymphatic catheters. Consequently, lymph and recirculating lymphocytes can be c ontinuously collected and this permits the quantitative assessment of local immune responses in these tissues, We have studied the lymphatic drainage pathways from the labial gingival tissues in sheep by two me thods. First, in a series of anatomical studies (n=6), a complex of Ev an's blue dye and albumin was injected into the labial gingival tissue s, One hour after injection the animals were sacrificed and the subman dibular and cervical regions were dissected to expose the stained lymp hatics. This anatomical study demonstrated 2 major drainage pathways: 1) cervical lymph ducts and; 2) efferent prescapular lymphatics. Secon dly, to compare the relative importance of these two drainage pathways , radiolabeled protein (I-125-albumin) was injected directly into the gingival tissues and its appearance in the cervical and prescapular ly mph was measured (n=7). Despite the technical difficulties encountered in the experiments, data collected showed that over 7.5 h, 64.7% of t he injected protein was recovered in the prescapular and cervical lymp h vessels (31.8+/-6.5% and 32.9+/-8.5%, respectively). Ln addition, 11 .9+/-2.1% of the injected protein was transported to the blood by rout es not involving the cannulated cervical and prescapular lymph vessels , With most of the remaining radiolabeled protein (17.9+/-4.9%) recove red from the injection site, we were able to account for approximately 95% of the injected protein, This study suggests that the lymph drain age from this region in the sheep model could provide one of the best described closed and contained systems and thus, could be a useful sys tem for future continous monitoring of inflammatory responses during e xperimental periodontal diseases.