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The thymus, a primary lymphoid organ and the initial site for development of T cell immunological function, is morphologically similar across species. It is actually an epithelial organ in which its epithelial cells provide a framework containing T cells as well as smaller numbers of other lymphoid cells. A symbiotic interaction exists between the thymic(More)
The National Toxicology Program (NTP) developed the chronic 2-year bioassay as a mechanism for predicting the carcinogenic potential of chemicals in humans. The cost and duration of these studies has limited their use to small numbers of selected chemicals. Many different short-term methods aimed at increasing predictive accuracy and the number of chemicals(More)
The thymus is a primary lymphoid organ that manifests dynamic physiological changes as animals age in addition to being exquisitely sensitive to stress and toxic insult. It is typically the first lymphoid tissue to respond to immunotoxic xenobiotics, with the first change being loss of cortical lymphocytes by apoptosis. This is followed by removal of the(More)
In 2005, the International conference on harmonization (ICH) recommended that all new human pharmaceuticals be tested for unintended immunomodulatory potential via a tiered approach. Included in this approach is a semiquantitative description of changes in the separate compartments of lymphoid tissue (also called enhanced histopathology). Chlorambucil was(More)
The morphology of the parathyroids in rats with hypergastrinemia, induced by antral exclusion, was compared with that of glands from untreated rats and animals from which the main source of gastrin- 17 was excluded (antral resection). Fourteen weeks after induction of hypergastrinemia the volume of the parathyroids was significantly increased owing to(More)
Immunotoxicology has developed into an integral regulatory requirement of the toxicological assessment of xenobiotics. Histopathological assessment of lymphoid tissues can provide genuine insight into perturbations of lymphoid cell populations. To facilitate retrospective examination of lymphoid organs should concerns over immunotoxicity be raised, we have(More)
Unexpected deaths occurred in studies involving a nude mouse model of mammary cancer that required subcutaneous implantation of 0.5 mg twenty-one-day release estrogen pellets for growth of the estrogen-dependent mammary tumor xenograft BT474c. Early deaths occurred in female nude mice and were associated with urinary retention, frequently with cystitis.(More)
Session 3 of the Toxicologic Pathology and the Immune System Symposium, presented as part of the 30th Annual Symposium of the Society of Toxicologic Pathology in 2011, focused on the biological advances in control of selected cellular and secretory components of acquired immunity. Acquired immunity goes beyond innate immunity to provide controlled(More)
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