MEHP opposed the seminiferous cord disrupting effect of ATRA. Representative images of cultured fetal testes exposed to a concentration range of MEHP with or without 10−6 M ATRA for 3 days, labeled with hematoxylin and eosin, or immunohistochemically labeled for smooth muscle alpha actin (ACTA2). 10−6 M ATRA caused seminiferous cord disorganization and loss of cord structure, but this effect was opposed by MEHP. ACTA2 was expressed only at the periphery of the ATRA-treated testes. MEHP co-exposure prevented the loss of ACTA2 deposition at seminiferous cord basement membranes that was observed in ATRA-treated cultures Scale bar = 200 µm. ATRA decreased the number of identifiable seminiferous cords per section, but cord number was increased in a concentration-dependent manner by MEHP. On x-axis, “−” indicates no ATRA; “+” indicates 10−6 M ATRA. Values reported in chart are mean ± SEM. n = 24 testes in vehicle control group and 6–7 testes per treated group. Bars not connected by the same letter are significantly different by 1-way ANOVA followed by Tukey’s post hoc test. Overall ANOVA p < .0001. The full-color image is available online.
