Female mice have more lymphoid follicles than male mice after chronic smoke exposure, and this effect was attenuated by ovariectomy. Representative images of a) vessel-associated, b) bronchial-associated and c) parenchymal-associated lymphoid aggregates in lung cross sections from smoke-exposed female mice were stained with H&E. Scale bar = 100 μm. The number of lymphoid aggregates per area (cm2) was quantified and compartmentalized (vessel-, bronchial- and parenchymal-associated) in lung sections of air-exposed (control) and smoke-exposed d) male, e) female and f) ovariectomized mice. g) Fractional area of lymphoid aggregates was quantified and normalized to the total lung cross-sectional area using the Aperio Imaging system. The number of lymphoid aggregates per area (cm2) was quantified and compartmentalized (vessel-, bronchial- and parenchymal-associated) in lung sections of H) air-exposed (control) male vs. female mice, and I) smoke-exposed male vs female mice. Values were expressed as mean ± SEM with N = 5–7 per group. Parametric t-test was performed in panels D-F and H-I. One-way ANOVA with Bonferroni’s multiple comparisons tests were performed in panel G.