The muscle, gland or organ cell capable of responding to a stimulus at the terminal end of an efferent nerve fiber Plasma cell, an effector B cell in the immune system Effector T cells, T cells that actively respond to a stimulus Cytokine-induced killer cells, strongly productive cytotoxic effector cells that are capable of lysing tumor cells[1] Microglia, a glial effector cell that reconstructs the Central nervous system after a bone marrow transplant[2] Fibroblast, a cell that is most commonly found within connective tissue[3] Mast cell, the primary effector cell involved in the development of asthma[4]