The gallbladder appears as a small, pear-shaped organ located on the right side of the body under the liver. It stores and concentrates bile. It is made up of layers of tissue: mucosa, muscular layer, perimuscular layer, and serosa. The mucosa is the inner layer consisting of epithelium and loose connective tissues. Layers of smooth muscles make up the muscular layer. The perimuscular layer is a connective tissue that covers the muscular layer. The outer covering of the gallbladder is the serosa.

Source:
The gallbladder. (n.d.). Canadian Cancer Society. https://cancer.ca/en/cancer-information/cancer-types/gallbladder/what-is-gallbladder-cancer/the-gallbladder#:~:text=The%20gallbladder%20is%20made%20up,that%20covers%20the%20muscular%20layer

The ileum is rich in lymphoid follicles. It is attached to the abdominal wall by the mesentery. The mucosa contains simple columnar epithelium consisting of enterocytes and goblet cells. It plays a role in enzymatic digestion of nutrients and absorption of vitamin B12, fats, and bile salts.

Source:
Karunaharamoorthy, A. (2022, March 7). Ileum. Kenhub. https://www.kenhub.com/en/library/anatomy/the-ileum

The esophagus connects the pharynx to the stomach. It is lined by moist pink tissue which is the mucosa. The mucosa consists of stratified squamous epithelium.

Source:
human digestive system – Esophagus. (n.d.). Encyclopedia Britannica. https://www.britannica.com/science/human-digestive-system/Esophagus