The medulla (chromaffin tissue) consists of somewhat purple or brown staining clusters of cells which lie internal to the zona reticularis and next to the medullary veins. Some of the sections in your slides show prominent nerve bundles (in cross section) in the medulla. These represent preganglionic sympathetic cholinergic axons which synapse with medullary cells.

T h y r o i d		8
	Slide Text The medulla (chromaffin tissue) consists of somewhat purple or brown staining clusters of cells which lie internal to the zona reticularis and next to the medullary veins. Some of the sections in your slides show prominent nerve bundles (in cross section) in the medulla. These represent preganglionic sympathetic cholinergic axons which synapse with medullary cells.