1. Rumen: This is the largest compartment and acts as a fermentation vat. It contains a vast population of bacteria and protozoa that break down cellulose from plant material. The rumen lining is composed of stratified squamous epithelium, which is a tough, protective layer.
2. Reticulum: This compartment is known as the "hardware stomach" because it traps and stores heavy objects, preventing them from entering the lower digestive tract. Its lining is similar to the rumen, with stratified squamous epithelium.
3. Omasum: This compartment has many folds that further break down food and absorb water. The omasum lining is made of stratified squamous epithelium with papillae, which are small projections that increase surface area.
4. Abomasum: This is the true stomach of the ruminant and is similar to the stomach of other mammals. It secretes digestive enzymes and acids to further break down food. The abomasum lining is composed of simple columnar epithelium, which contains specialized cells for secreting gastric juices.
Overall, the stomach lining of an ox or cow is adapted for digesting a diet rich in cellulose. The multiple compartments and their unique linings allow for efficient fermentation, mechanical breakdown, and absorption of nutrients.