The lymphatic system consists of lymph vessels, lymph nodes, and lymphocytes. Lymph vessels circulate lymph fluid through the body and drain into two main ducts in the neck. Lymph nodes along the vessels filter bacteria and foreign bodies from the lymph. The spleen, thymus, tonsils, and other lymphoid tissues also aid the immune system. The endocrine system is made up of ductless glands that secrete hormones directly into the bloodstream, including the pituitary gland, thyroid gland, parathyroid glands, adrenal glands, pancreas, testes, and ovaries. These glands regulate processes throughout the body by producing hormones like insulin, estrogen, and adrenaline.