ABSTRACT
It is commonly perceived that the brain composes of glia and neuron cells (GNR) in the ratio of 10:1. However, a recent review suggested that the GNR could be only about 1:1 (von Bartheld, Bahney, and Herculano-Houzel 2016). In the human cerebral cortex, there are about 10–20 billion neuronal cells, while the number of glial cells could be about 15–30 billion. There are three types of glial cells in the human cerebral cortex with 45–75% of them are oligodendrocytes, 19–40% are astrocytes, and 10% or less are microglia (von Bartheld, Bahney, and Herculano-Houzel 2016).
