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. 2023 Jun 21;131(6):067010. doi: 10.1289/EHP12034

Figure 1.

Figure 1A is a schematic illustration depicting long-term MC-LR oral exposure in vivo. Four-week-old CD-1 female mice treated with 1 times P B S or MC-LR 10 micrograms per kilogram of body weight on a daily oral gavage for 6 weeks leads to changes in body weight, estrous cyclicity, ovarian histology, follicle count, and corpora lutea counting. Figure 1B is a line error bar graph titled Body weight, plotting Weight (grams), ranging from 20 to 32 in increments of 2 (y-axis) across days of treatment, ranging from 1 to 7 in increments of 6, 7 to 35 in increments of 7, and 35 to 41 in increments of 6 (x-axis) for control and MC-LR. Figure 1C is a set of two graphs. On the top, a line graph titled Estrous cyclicity, plotting Estrous cycle, ranging from metestrus, estrus, proestrus, diestrus (y-axis) across day, ranging from 1 to 13 in increments of 3 (x-axis) for control and MC-LR. At the bottom, a bar graph, plotting Estrous cycle days, ranging from 0 to 8 in increments of 2 (y-axis) across proestrus, estrus, metestrus, diestrus (x-axis) for control and MC-LR. Figure 1D is a set of two stained tissues, titled Control and MC-LR, depicting corpora lutea (C L); primordial follicles (Prim); primary follicles (Pri); and secondary follicles (Sec), each with a scale bar of 200 micrometers. Figure 1E is a bar graph, titled Follicle development, plotting Number of follicles per ovary, ranging from 0 to 1,000 in increments of 200 (y-axis) across primordial, primary, secondary, antral, and atretic, each for control and MC-LR (x-axis) for control and MC-LR. Figure 1F is a bar graph titled Corpus luteum, plotting Number of corpora lutea per ovary, ranging from 0 to 20 in increments of 5 (y-axis) across Control and MC-LR (x-axis).

Assessment of mouse body weight, ovarian cyclicity, and folliculogenesis following a long-term, low-dose oral exposure to MC-LR. (A) The schematic of long-term MC-LR oral exposure in vivo. N=5 mice in each group. (B) Effect of MC-LR on mouse body weight during the 6-wk treatment. Average daily body weight in 1× PBS- or MC-LR–treated mice. (C) Representative 14-d estrous cyclicity (top) and the numbers of days in each estrous cycle stage (bottom) in the last 2 wk of 1× PBS or MC-LR treatment. (D) Representative ovary histological images after 6-wk 1× PBS or MC-LR treatment. Red squares indicate corpora lutea (CL); green squares indicate primordial follicles (Prim); orange squares indicate primary follicles (Pri); and blue squares indicate secondary follicles (Sec). (E) Total numbers of various stages of follicles per ovary in 1× PBS- or MC-LR–treated mice. (F) Total numbers of CL per ovary in 1× PBS- or MC-LR–treated mice. N=5 mice in each group. Data were analyzed with two-way ANOVA with Bonferroni’s post-test (B) and Student’s t-test (C,E,F). Bidirectional error bars represent mean±standard deviation; *p<0.05. Data in (B,C,E,F) are also presented in Tables S2–S5, respectively. Note: ANOVA, analysis of variance; D, diestrus; E, estrus; M, metestrus; MC-LR, microcystin-LR; P, proestrus; PBS, phosphate-buffered saline.