Mucin is produced in goblet cells which are found in the lining of various mucous membranes throughout the body. These include:

* Respiratory tract: The lining of the nose, sinuses, trachea, bronchi, and bronchioles

* Digestive tract: The lining of the mouth, stomach, intestines, and gallbladder

* Reproductive tract: The lining of the uterus, fallopian tubes, and vagina

* Urinary tract: The lining of the bladder and urethra

* Conjunctiva: The lining of the eyelids and the surface of the eye

While goblet cells are the primary producers of mucin, other cell types, such as submucosal glands, may also contribute to mucin production in some locations.