title: Characterization of age- and gender-related changes in the spleen and thymus from control cynomolgus macaques used in toxicity studies.
abstract: 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.
authors.affiliation: Colorado State University, Fort Collins, Colorado, USA.
authors.forename: Melanie S
authors.initials: MS
authors.lastname: Spoor
authors.forename: Zaher A
authors.initials: ZA
authors.lastname: Radi
authors.forename: Robert W
authors.initials: RW
authors.lastname: Dunstan
mesh_terms: D000375:Aging / Q000502:physiology*; D000818:Animals; D035061:Control Groups; D005260:Female; D007150:Immunohistochemistry; D008252:Macaca fascicularis; D008297:Male; D009929:Organ Size; D012737:Sex Factors; D013154:Spleen / Q000166:cytology*; D013950:Thymus Gland / Q000166:cytology*; D018675:Toxicity Tests / Q000379:methods*