The reticulorumen (UK: /rəˈtɪkjʊləˌruːmən/; rə-TIK-yuu-lə-roo-mən) represents the first two chambers in the alimentary canal of ruminant animals.
The rumen wall is covered in small, finger-like projections called papillae, whereas the reticulum is lined with ridges that form a hexagonal honeycomb pattern.
[citation needed] Despite the differences in the texture of the lining of the two parts of the reticulorumen, it represents one functional space.
Microbial fermentation degrades otherwise indigestible polymers in the reticulorumen to volatile fatty acids (VFAs), methane, and carbon dioxide.
[1] This fermentation is anaerobic, and allows the microbes in the reticulorumen to derive energy and amino nitrogen for growth and reproduction.