Cerebellum tissue. Light micrograph of a section through the cerebellum of the brain. The cerebellum comprises three main layers. The outer grey matter (cortex) comprises the molecular layer (dark yellow) and the granular layer (orange). Within the grey matter is the white matter (bright yellow). Purkinje cells (flask-shaped) exist at the junction of the molecular and granular layer. The cerebellum controls balance, posture and muscle coordination.