Photomicrograph of lymphatic follicle of white pulp in spleen. The expression of B-lymphocyte antigen (CD19) (black arrow) has shown (A) positive expression with intensive quantity (yellow arrow) at the center in control group, (B) weak expression in follicle area with intensive quantity (yellow arrow) at the center of hypothyrodism group, (C) positive expression in the SC-SeNPs group, (D) low-intensity expression in the levothyroxine group, and (E) positive expression in the SC-SeNPs+levothyroxine group. Hematoxylin & DAB. 100x.