PTGS2 and hyperthyroidism: In contrast, hyperthyroidism at 19 days of gestation showed an increase of the area and intensity of COX-2 immunohistochemical expression in the CL compared to the control group (P < 0.05), while at 10 and 14 days of gestation no significant differences were noted (p > 0.05) (Figure 4B and 4C).