Endocrine Pertaining to glands that lack ducts, or to their effects on the body. Many major hormone systems are classified as endocrine.
Exoskelatinous Having an exoskeleton, or external skeleton (in contrast to an internal skeleton, AKA bones).
Neurotransmitter A natural chemical used to carry signals between nerve cells.
Primate A vertebrate order that includes humans, apes, monkeys and lemurs; marked by similar limb and tooth structure and superior thinking ability.
Receptor A structure on the surface of a cell that can lock onto certain molecules, used to carry a signal through the cell wall.
Stain A chemical used in microscopy to identify certain types of cells or structures.
Vestigial Relating to an organ or structure that no longer functions, even though its structure still exists.
Yenta Yiddish for "matchmaker."
