Characters
The series makes use of recurring human characters originally from both Once Upon a Time... Man and Once Upon a Time... Space. Every character in the series appeared as a real person (the old intelligent doctor, the dedicated blonde mother, the boy and the girl, their obese friend, and the pair of bullies) and anthropomorphic representations of cells and cellular functions within the human body.
The manager of the brain – represented by Maestro, the bearded old man.
The manager of the cell nucleus – represented by Maestro, usually asleep in his chair.
Enzymes – The human body's workmen, shown usually as a man in a bib overall and a baseball-type cap.
Digestive enzymes – Works of digestion. Some enzymes are shown as female and most as male. The females are only seen in the stomach. The males appear in the stomach and small intestine.
Hormones – messengers for the body, represented as humanoid robotic outboard motors spray-painted according to function; those representing thyroxine are given life by iodine. These hormones are all female.
Red blood cells – represented by red humanoids. Most notable is elderly Professor Globus, who tells a lot about how the body works; he is accompanied by dimwitted big boy called Hemo; and his inquisitive and mischievous friend Globin. They can be pink colored when they carry oxygen bubbles or carbon dioxide bubbles in a back pouch, becoming dark red when carrying carbon dioxide.
Neurotransmitters – The blue speedy guys that can deliver messages as papers or passengers through nerves and stations. They are mostly running anytime on delivery, and pick up or drop off passenger times until they reach the end.
Platelets – represented as red disks with a face, legs and four arms.
White blood cells – The body's police force.
Neutrophil granulocytes – represented by foot-patrol "policemen" which are completely white in color, and wear a yellow star badge. They carry batons and swallow any bacterias that they find. They can clone themselves. Most of the time they function as traffic cops. Their commander is the same but with a Caucasian head, and is named Jumbo or Jumbo Junior.
Lymphocytes – represented by:
Lymphocytes B – as marshals in a small one-man round flying craft with two aimable side-mounted hydrojet propulsors; two of them are a version of Peter and Psi (named Captain Peter and Lieutenant Claire). Some other (unnamed) B cell pilot characters each appear more than once, for example a spotty-faced teenage boy. They can drop antibodies from an underbelly bomb bay. They can multiplicate themselves through mitosis duplicating the craft and the pilot. Their uniforms are very light blue with shoulder pads. (Those uniforms appear in the outside world in a few futuristic scenes as astronaut uniforms/undersuits.)
Lymphocytes T – the same sort of craft but with a large uppercase T on the underbelly at the bow. They can discharge a purple smoke that kills bacteria and cancer cells.
Phagocyte – hovering spherical craft with several large suction tubes coming out of them. A pilot's head can be seen through a small canopy on top. They can engulf bacteria.
Basophils – plump women with body like granulocytes, who instead of swallow bacterias carry a basket of "histamine grenades" and throw them to attack toxins.
Macrophages – (a big yellow ground vehicles shaped like frog heads with a big front scoop grab and three wheels; each "eye" is a small canopy revealing a pilot's head), "the cleaning services of the body". Most of the time they function by removing the body' waste and during emergency times they phagocyte bacteria and viruses.
Immature leucocytes: teenage humanoids with the same uniform as the lymphocyte B pilots: seen in the thymus, which is represented as a police training college. In the Bone Marrow episode, some of them are shown to become rebellious and destructive, attacking other members of the body due to Leukemia.
The antibodies – a small white insectoid characters which after being launched at infectious agents, fly around the bacteria or viruses and paralyze them. Their commander is named Metro. A variant of them, wearing fake large noses and carrying a fencing foil, are specialized in fighting thetanus toxins.
The Pathogens are the main antagonists of the series. They are the characters that make people sick. The other antagonists are the Immature leukocytes in Bone Marrow,
The bacteria (represented as blue bullies) – the big bully. Mostly blue in color.
The viruses (represented as yellow worms with hands) – the smaller bully. Mostly yellow in color.
Organic molecules, which are represented in two cases as characters.
Fats/Fatty acids: Represented as fat yellow ponies.
Proteins: Represented as a tall, strong, and muscular orange character in overalls with some doglike features.
Sugars: Small green-and-purple hexagons and pentagons. Sometimes appear as candylike characters.
Amino acids: Similar appearance to antibodies, generally invisible until the episode dealing with protein synthesis.
DNA/RNA: Represented quite accurately and in detail when explaining protein synthesis.
Vitamins: Represented as colored living letters. As seen in the lymphatic system, P is present but rarely.
Cholesterol: Yellow seal-like characters that can block a passage of a blood vessel. As seen in "The liver factory", the cholesterol accumulated around Jumbo, blocking the passage of the red blood cells in the blood vessel.
Gall/Bile : Blue-green-colored liquid that makes the fats shrink, as seen in "The digestion".
The series describes a "society inside the body" with a strong pyramidal stratification of work.
