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Characterization of Age- and Gender-related Changes in the Spleen and Thymus from Control Cynomolgus Macaques Used in Toxicity Studies
1 Colorado State University, Fort Collins, Colorado, USA Correspondence: Zaher A. Radi, DVM, MS, MBA, PhD, DACVP, Drug Safety Research & Development, Pfizer Global R&D, 700 Chesterfield Parkway West, Building BB371-2 (BB3N), Chesterfield, MO 63017, USA; e-mail:zaher.radi{at}pfizer.com. Age- and gender-related lymphoid tissue variability in control male and female monkeys of various ages (under three years; three to six years; seven to fifteen years) was characterized. Spleen and thymus organ weights, organ-to-body and organ-to-brain ratios, morphology by light microscopy, and B- and T-cell immunohistochemistry (IHC) were evaluated. Splenic weights and ratios were not significantly different between various age groups or genders, except males and females in the three-to-six-years age group, who exhibited statistically significant changes from the under-three-years age group. No differences in the number of primary follicles, secondary follicles with germinal centers, B-cell follicles, and periarterial lymphoid sheath were seen between age groups or genders, and no trends were noted in the spleen. By IHC, no differences were observed in B- and T-cell splenic densities. Several age- and gender-related changes in weights and ratios were noted in the thymus. The thymus had a trend toward increased interlobular fat infiltration with increasing age in both males and females. Thymic delineation of the cortex and medulla was significantly decreased in the seven-to-fifteen-years age group for males only. The cortex-to-medulla ratio was significantly lower only in males in the seven-to-fifteen-years age group. B- and T-cell cellular density did not change across various ages.
Key Words: immunohistochemistry nonhuman primate spleen thymus
This version was published on July
1, 2008 Toxicologic Pathology, Vol. 36, No. 5,
695-704 (2008) |
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