ACOX1 and hypothyroidism: Closely adjacent to the ER, ACOX3-positive peroxisomes showed exclusive pattern: absence on day 15, single ACOX3-positive peroxisomes presence on day 7, and double ACOX1/ACOX3-positive peroxisomes presence in euthyroid control and on days 7 and 21 of hypothyroidism (figure 5b).