Section through the motor (precentral) cortex of a monkey’s brain, stained with methylene blue. Note (in comparison with the sensory cortex) the relatively greater thickness of the motor cortex, the presence of the giant Betz cells in the lamina ganglionaris, and the absence of a lamina granularis interna. The Betz cells give rise to some (but only to some) of the fibres of the pyramidal tract. Note the following layers in the cortex – 1. Lamina zonalis. 2. External granular layer (very indistinctly differentiated). 3. Lamina pyramidalis. 4. Lamina ganglionaris (with giant pyramids). 5. Lamina multiformis. The photograph is at a magnification of X 54.

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