Reticulum (anatomy)

Second compartment of the ruminant stomach

This article is about the organ in anatomy. For other uses, see Reticulum (disambiguation).

Diagram of the four-chamber alimentary canal of a ruminant.

The reticulum is the second chamber in the four-chamber alimentary canal of a ruminant mammal. Anatomically it is the smaller portion of the reticulorumen along with the rumen. Together these two compartments make up 84% of the volume of the total stomach.

The reticulum is colloquially referred to as the honeycomb, bonnet',[1] or kings-hood.[1] When cleaned and used for food, it is called "tripe".

Heavy or dense feed and foreign objects, such as pieces of metal will settle here. It is for this reason that it was nicknamed in Irish as sparán na bhfeoirlingí (lit. 'purse of farthings') or goile na bhfeoirlingí ('stomach of farthings'). It is the site of hardware disease in cattle, and because of the proximity to the heart this disease can be life-threatening.[2][3]

## Anatomy

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Reticulum beef tripe Mucosa of the reticulum of a sheep.
1\. esophageal opening
2\. lips of reticulum
3\. Cristae reticuli (reticular crest)
4\. reticulo-omasial opening

The internal mucosa has a honeycomb shape. When looking at the reticulum with ultrasonography it is a crescent-shaped structure with a smooth contour.[4] The reticulum is adjacent to the diaphragm, lungs, abomasum, rumen and liver. The heights of the reticular crests and depth of the structures vary across ruminant animal species.[5] Grazing ruminants have higher crests than browsers. However, general reticulum size is fairly constant across ruminants of differing body size and feeding type.

Why nature selected the honeycomb shape as the internal mucosal structure of the reticulum. The main function of the reticulum is to store higher-density particles and generate biphasic contraction for the separation of food particles governed by the large amount of water in the reticulum. In The internal anatomical structure of the reticulum, the Honeycomb resembles the classical organic benzene structure; it is the most favourite structure of the nature. A hexagon has six sides, which allows it to distribute forces evenly across its structure, making it more stable and resistant to deformation. Additionally, the angles of a hexagon are evenly spaced, which helps to evenly distribute stress and prevent weak points, it has the angle that releases the most tension i.e.;120 degrees. The hexagon uses the least amount of material to hold the most weight that’s why higher density particles remain stay in the reticulum. High density particles may settle into the honeycomb structures and can be found after death. It is during the contractions of the reticulum that sharp objects can penetrate the wall and make their way to the heart. The hexagon is considered one of the strongest shapes in nature due to its ability to distribute force evenly and efficient. Hexagonal structures allow water molecules (with their one atom of oxygen and two of hydrogen) to group up together in the most efficient way and help in food particles separation.[6]

In a mature cow, the reticulum can hold around 5 gallons (20 litres) of liquid. The rumen and reticulum are very close in structure and function and can be considered as one organ. They are separated only by a muscular fold of tissue.

In immature ruminants, a reticular groove is formed by the muscular fold of the reticulum. This allows milk to pass by the reticulorumen straight into the abomasum.

## Role in digestion

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The fluid contents of the reticulum play a role in particle separation. This is true both in domestic and wild ruminants. The separation takes place through biphasic contractions. In the first contraction, there is sending large particles back into the rumen while the reticulo-omasal orifice allows the passage of finer particles. In the second contraction, the reticulum contracts completely so the empty reticulum can refill with contents from the rumen. These contents are then sorted in the next biphasic contraction.[5] The contractions occur in regular intervals. High density particles may settle into the honeycomb structures and can be found after death. It is during the contractions of the reticulum that sharp objects can penetrate the wall and make their way to the heart. Some ruminants, such as goats, also have monophasic contractions in addition to the biphasic contractions.

## See also

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* Methanogens in digestive tract of ruminants

## References

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1. ^ a b "chambersharrap.co.uk". www.chambersharrap.co.uk.
2. ^ "Foclóir Gaeilge–Béarla (Ó Dónaill): sparán na bhfeoirlingí". www.teanglann.ie.
3. ^ "reticulum - Aistriúchán Gaeilge ar reticulum (An Foclóir Nua Béarla-Gaeilge)".
4. ^ [Braun, U., and D. Jacquat. 2011. Ultrasonography of the reticulum in 30 healthy Saanen goats. Acta Veterinaria Scandinavica 53:19]
5. ^ a b [Clauss, M., Hofmann, R. R., Streich, W. J., Fickel, J., and Hummel, J. 2009. Convergence in the macroscopic anatomy of the reticulum in wild ruminant species of different feeding types and a new resulting hypothesis on reticular function. Journal of Zoology. 281:26-38.]
6. ^ Makar, A. B.; McMartin, K. E.; Palese, M.; Tephly, T. R. (June 1975). "Formate assay in body fluids: application in methanol poisoning". Biochemical Medicine. 13 (2): 117–126\. doi:10.1016/0006-2944(75)90147-7. ISSN 0006-2944. PMID 1.

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*[lit.]: literal translation