light microscopic pictures of thyroid gland from sham operated rats. (a) Large peripheral thyroid follicles (thick arrows) under the capsule (caps) lined with flattened and cuboidal epithelial lining (thin arrows) filled with colloid (C). The central follicles appear smaller in size (Hx&E × 200). (b) Higher magnification of the central zone from the previous section. The epithelial lining of the follicles is cuboidal (thin arrows) with rounded central or basal nuclei. The follicles are variable in size. The colloid contains peripheral vacuolization (arrow heads) (Hx&E × 400). (c) The central zone of thyroid of sham-operated rats showing variable amount of colloid filling the lumina of the follicles (C) (PAS × 400). (d) There is minimal amount of connective tissue in between the follicles (thin arrows) (Masson trichrome × 400).