Histology of the complex ruminant stomach (Day 162)

Vet School Diary Histology Bovine Rumen Section under the Microscope

Today’s Diary Entry is sponsored by Find Pet Boarding

Start of my second week of my second semester, last week vanished in a blur and this week I have tried to plan my time better to get a lot more of the research for my Emergency First Aid for Animals book completed.

Now I think I have previously said before how the stomach with ruminants is divided into four different compartments; the rumen and reticulum, omasum and the abomasum. Each of these has a specific role to play in digestion and specific structure to match. This is known as the complex stomach and the esophagus enters this between the reticulum and rumen. The rumen is the largest stomach compartment and is connected to the reticulum with a large opening allowing food to be passed back and forth between the two. Remembering that ruminants eat plant matter the rumen is where fermentation takes place with a large amount of bacteria and protozoa act on the contents breaking it down. The surface of this is covered in small papillae (low conical projections) and looks like this.

Vet School Diary Histology Bovine Rumen Section under the Microscope
Bovine Rumen Histology

The reticulum has a honeycomb like structure and sits next to the rumen and starts the mechanical breakdown of food into fine particles. This compartment is usually involved in “hardware disease” where cows swallow screws, nails wire or other hardware and it embeds into the lining. Occasionally this will completely penetrate the reticulum lining causing disease and as the reticulum sits next to the diaphragm will head into the thorax towards the heart.

Vet School Histology Section of Bovine Reticulum with Honeycombe structure
Histology of Reticulum showing a cell from the honeycomb structure

The last structure unique to compound stomach is the omasum which is where the final stage of mechanical digestion takes place before the plant matter enters to Abomasum which is basically the same as a simple stomach. The lining of the omasum consists of really large muscular folds which help the mechanical breakdown of food into tiny particles suitable for digestion in the stomach and intestine. Below you can see the size of these folds in relation to the Rumen and Reticulum (its so big I’ve had to put multiple different pictures together to make it!)…

Histology section of the bovine omasum showing the folds in the mucus tissue
Histology section of the folds in the omasum of the cow

After this the food then enters the abomasum which is the same as the simple glandular stomach and enzymes and gastric juices start to digest the food here before it then enters the small intestine.

This afternoon in Physiology we finished up looking at the endocrine system which is responsible for controlling the body systems using chemical messengers (aka hormones). There are several different hormones and I do have plans to do a diary entry in depth on each hormone in the near future so will leave this here until then.

ProVet Cloud Practice Management System

Leave a Reply

Your email address will not be published. Required fields are marked *

*