A solution of fractionated, dead, or attenuated live pathogenic material that is introduced into an individual for the purpose of stimulating a primary immune response or \"boosting\" a previously produced anamnestic state.

A membrane-bound organelle in which water soluble nutrients and wastes are stored.

The tenth cranial nerve; it innervates the pharynx, larynx, heart, lungs, and abdominal viscera. Responsible for maintaining homeostatic activity.

The tube carrying sperm from the testis to the urethra in mammalian males.

Two large veins, the superior vena cava and the inferior vena cava, that return deoxygenated blood from the periphery to the heart (right atrium).

Pertaining to the under surface or front surface of an organism.

The chambers of the heart that pump blood into pulmonary and systemic circulation.

Member of the phylum chordata possessing a backbone composed of vertebrae (member of subphylum vertebrata).

Referring to an organ or limb that has no apparent function now but was functional at some time in the organisms evolutionary past.

A small projection from the wall of the small intestine that increases the surface area for digestion and absorption.

Substituent on a double bonded carbon atom (ie. an enol is a vinylic alcohol).

A tiny, organism like particle composed of protein encased nucleic acid; viruses are obligate parasites.