Opposition

A special movement that allows the Thumb to touch or oppose each of the other Fingers.

oocyte

Immature Ova.

Oligodendrocyte

Neuroglial Cell that forms Myelin Sheaths in the CNS.

Olfactory Receptor

Receptor in the Superior part of the Nose responsible for sense of smell.

Oblique Fissure

A Fissure in the Lungs that runs down and forward, separating the left Lung in to an upper and lower Lobe and separating the upper and middle Lobes from the lower lobe in the right Lung.

Nucleus

A rounded or oval Mass of Protoplasm within the Cytoplasm of a Cell  the center of the Atom; in the nervous system, denotes a group of Nerve Cell Bodies in the Brain of Spinal Cord.

Nucleic Acids

Large organic Molecules with Carbon, hydrogen, oxygen, nitrogen and phosphorous Important for storing and processing information in every Cell.

Nuclear Membrane

A Membrane that surrounds the nucleus of a Cell; also know as Nuclear Envelope.