STOCKHOLM, Feb. 20 -- Scientists at Sweden's Karolinska Institute have produced a detailed map that identifies 47 different kinds of cell types.

The findings by a group of scientists led by professor Sten Linnarsson were outlined in the journal Science.

"If you compare the brain to a fruit salad, you could say that previous methods were like running the fruit through a blender and seeing what color juice you got from different parts of the brain," said Linnarson, who is a senior researcher at Karolinska's department of medical biochemistry and biophysics.

"But in recent years," Linnarsson continued, "we've developed much more sensitive methods of analysis that allow us to see which genes are active in individual cells. This is like taking pieces of the fruit salad, examining them one by one and then sorting them into piles to see how many different kinds of fruit it contains, what they're made up of and how they interrelate."

By studying over three thousand cells from the cerebral cortex in mice, one at a time and in detail, and comparing which of the 20,000 genes were active in each one, the scientists were able to sort the cells into virtual piles.

They identified 47 different kinds of cell, including a large proportion of specialized neurons, some blood vessel cells and glial cells, which take care of waste products, protect against infection and supply nerve cells with nutrients.

"This map will be an invaluable resource for researchers around the world as they carry out detailed studies on brain cells at times of health and illness," Christer Betsholtz, a professor at the Uppsala University's department for immunology, genetics and pathology, told local newspaper UNT.