Palatine tonsil. Light micrograph of a section through the surface of a palatine tonsil. These tonsils are filters that keep the immune system in check. They are found at the back of the mouth and contain lymphoid follicles. The lymphoid follicles (large pale pink circles, lower right and centre left) house the immune system's B cells (B lymphocytes) and antibodies. Bands of connective tissue (blue) known as trabeculae support the lymph node.s interior. A blood vessel (purple ring) is seen within the connective tissue at centre right. Azan stain. Magnification: x30 when printed 10cm wide.