These live action sequences are interspersed with an animated story that takes place within Frank's body. Chris Rock provides the voice of the title character, a white blood cell. The body is portrayed as a city: the brain is city hall, the bowels are the slums, etc. Osmosis Jones is depicted as a cop, whose job is to take down any germs that enter the body. When Frank's illness progresses, he takes a cold pill. David Hyde Pierce does the voice of that cold pill, named Drix, who helps Jones fight the germs.

A cold tablet and a white blood cell team up to fight germs in Osmosis Jones

The picture goes back and forth, showing the physical effects of Frank's sickness as it evolves into a full-fledged virus, then using animation to show what is happening in different parts of his body. When he develops a case of the sweats, the camera zooms in on his armpit. Then we get a scene set inside his sweat glands, as Jones and Drix shake down one of his glands for information on the virus. Called Thrax, and voiced by Laurence Fishburne, the virus travels through Frank's body, infecting everything in its path, making its host body sicker and sicker as the movie goes on.

The ingenious thing about Osmosis Jones is the way it imagines the inner workings of the human body as a city. William Shatner does the voice of the "mayor" (a.k.a. Frank's conscience), which tells him to eat bad foods and skip exercise. He also proudly announces that "construction is about to begin on a third chin." As Frank considers his daughter's requests to get healthy, we learn that the mayor has an opponent for office. He is Tom Colonic, and his platform promises to make things better for the bowels by introducing fiber, fruit, and vegetables.

I also liked the way Frank's dreams manifest themselves in his body as movies. Cells go to the "theater" to see Frank's subconscious thoughts. The posters in the lobby advertise titles such as "He Forgot His Pants!" There are probably a thousand little jokes and puns like that. This is the kind of movie you have to buy on DVD so you can freeze-frame it to look at all the details.

The live action scenes were directed by Peter and Bobby Farrelly, who did There's Something About Mary and Me, Myself & Irene. Piet Kroon and Tom Sito directed the animation. Interestingly, the animated scenes are gorgeous to look at. They are vibrant and colorful. The live action scenes, on the other hand, are as grungy as Frank is. The effect, I believe, is intentional. Either way, it adds a lot.

Osmosis Jones is not the first movie set inside the human body, but it takes a fresh approach. This is a good movie for kids, who can learn a thing or two about how the immune system works while still being entertained. The adults, though, will have the most fun. The film contains a subversive streak and is filled with gags certain to go over the heads of children (i.e. a sign in a bakery window advertises "pus cookies"). No point in spoiling too many of them here. There are too many to list anyway. Osmosis Jones throws them at you left and right, in an explosion of verbal and conceptual creativity. This movie is witty, smart, and hysterically funny.

( 1/2 out of four)

Osmosis Jones is rated PG for bodily humor. The running time is 1 hour and 38 minutes.