Gallbladder with epithelium, connective tissue, and smooth muscle (100X)

The innermost layer facing the lumen, where bile is stored, is the epithelial layer. It appears as a slightly darker pink band above the underlying lamina propria, which consists of loose connective tissue.

Scattered throughout the connective tissue are bundles of smooth muscle fibers. These fibers enable the gallbladder to contract and release the stored bile.