ductless gland, endocrine gland, endocrine - any of the glands of the endocrine system that secrete hormones directly into the bloodstream

immune system - a system (including the thymus and bone marrow and lymphoid tissues) that protects the body from foreign substances and pathogenic organisms by producing the immune response

cervix, neck - the part of an organism that connects the head to the rest of the body; "he admired her long graceful neck"