Mandibular lymph node

Mouse (B6C3F1) 16 d 5 d/wk (GO) 730 M 1450 F 1450M (mild lymphoid depletion of thymus) 2900 (lymphoid depletion and necrosis of the spleen and thymus necrosis of the mandibular lymph node) NTP 1994 TCP... 

In the NTP-sponsored intermediate-duration oral study using Fischer 344 rats and B6C3F, mice, dose-related leukopenia and lymphopenia were observed for both male and female Fischer 344 rats at 200 and 600 mg/kg/day killed on day 60, and at all doses in female rats killed on day 120 (NTP 1986). Decreased leukocytes were observed in male and female rats exposed for 60 days to 200 and 600 mg/kg/day benzene. Lymphoid depletion in the B-cell of the spleen was observed in animals exposed to 200 mg/kg/day (3 of 5 males, 4 of 5 females) and 600 mg/kg/day (5 of 5 males, 5 of 5 females) benzene for 60 days and in animals that received 600 mg/kg/day (10 of 10 males, 10 of 10 females) benzene for 120 days. At 600 mg/kg/day benzene exposure, increased extramedullary hematopoiesis was observed in the spleen of 4 of 5 male and 3 of 5 female rats. Dose-related leukopenia and lymphopenia were observed for both male and female mice exposed for 120 days, but not for 60 days. Leukocytes and lymphocytes were significantly decreased in male mice exposed for 120 days to 50, 100, 200, 400, and 600 mg/kg/day benzene. At 120 days of exposure, leukocytes significantly were decreased in female mice at 600 mg/kg/day and lymphocytes at 400 and 600 mg/kg/day. Histological examination revealed no adverse effects in mandibular lymph node or the thymus for either rats or mice (Huff et al. 1989 NTP 1986). Rats exposed to benzene at 50 and 100 mg/kg/day for 6 months had significant leukopenia (Wolf et al. 1956). 

Increased popliteal, axillary, and mandibular lymph node weight 450 Michielsen et al. (1997, 2002)... 

The mesenteric lymph node and typically the mandibular lymph node are collected in most short-term and chronic toxicity studies. Both nodes tend to be highly reactive because they drain mucosal surfaces that frequently encounter microbes introduced via the oral cavity. Because the mesenteric node drains the gastrointestinal tract, this node is viewed as an indicator of direct, as well as systemic, toxicity in cases of oral dosing of compound. A practical issue with the mesenteric node is that of its extensive length and the normal variability encountered depending on the section of the node that is examined (Figure 2.2-14). Numerous secondary follicles with germinal centers... 

Information on immunological/lymphoreticular effects in test animals is limited to histopathological examination of tissues after intermediate-duration inhalation exposure to -hexane. No treatment-related lesions were observed in the cervical, bronchial, or mesenteric lymph nodes, thymus, bone marrow (sternum), or spleen of male Sprague-Dawley rats exposed to 500 ppm -hexane 22 hours a day for 6 months (IRDC 1981) or in mandibular and mesenteric lymph nodes, thymus, bone marrow, or spleen of Fischer 344 rats of both sexes exposed to up to 10,000 ppm for 6 hours a day, 5 days a week for 13 weeks (Cavender et al. 1984). Similar results were observed in mesenteric lymph nodes, thymus, bone marrow (sternum), and spleen in B6C3Fj mice exposed to -hexane at concentrations up to 10,000 ppm for 6 hours a day, 5 days a week for 13 weeks or 1,000 ppm for 22 hours a day, 5 days a week for 13 weeks (Dunnick et al. 1989 NTP 1991). 

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