Learning Objectives

Identify the three distinct layers of the cerebellar cortex. Recognize the unique morphology of Purkinje cells. Distinguish between the Molecular and Granular layers. Understand the functional circuitry of cerebellar coordination.

Histology of the Cerebellum

The cerebellum (“little brain”) has a highly regular, repetitive histological structure designed for the rapid processing of motor and sensory information.

• Molecular Layer (Outer): The superficial layer containing few cell bodies but many unmyelinated axons (parallel fibers) and the dendritic trees of Purkinje cells. It appears relatively pale in H&E sections.
• Purkinje Cell Layer (Middle): A single, thin layer of massive, flask-shaped neurons. These are the only output cells of the cerebellar cortex, sending inhibitory (GABAergic) signals to the deep cerebellar nuclei.
• Granular Layer (Inner): Highly cellular and intensely basophilic (dark purple) due to the presence of billions of tiny Granule cells. This is one of the most neuron-dense regions in the entire brain.
• White Matter Core: Located deep to the granular layer, consisting of myelinated fibers (afferent mossy and climbing fibers, and efferent Purkinje axons).

Cerebellar Layer Summary

Activity