light microscopic pictures of thyroid gland of group III (ovarictomized rat treated with estradiol). (a) The peripheral follicles (thick arrows) under the capsule (caps) are relatively larger than the central follicles (Hx&E × 200). (b) Higher magnification of the central zone showing very small follicles. Some follicles have no apparent lumina (thick arrows), while others contain absent or highly vacuolated colloid material (arrow heads) (Hx&E × 400). (c) There is little amount of the colloid in some follicles (C) while others demonstrate absent colloid (thin arrows) (PAS × 400). (d) There is minimal connective tissue (thin arrows) surrounding the thyroid follicles (Masson trichrome × 400).