The trachea is the tube linking the cricoid cartilage of the larynx to the bronchi, forming part of the conducting system which transports air from the external environment to the lungs.


The thymus consists of two poorly encapsulated lobes which arise in the embryo as separate primordia on each side of the midline in the neck region. During ontogeny, the organ migrates caudally and medially to the superior mediastinum where the two lobes become closely connected, although they do not appear to fuse. The relative weight is largest about a week after birth; the absolute weight is largest at about the age of 2 months and then gradually declines. In old rats, especially in preterminal condition, the organ can be so small that it is hardly recognizable in the mediastinal fat tissue.


The esophagus (or gullet) is a muscular tube which transports food from the pharynx to the stomach. A bolus of food is passed down the oesophagus by peristalsis. The oesophagus is divided into cervical, thoracic and abdominal sections.


Rat lungs have several lobes

Thoracic diaphragm

The thoracic diaphragm, or simply the diaphragm, is a sheet of internal skeletal muscle in humans and other mammals that extends across the bottom of the thoracic cavity. The diaphragm separates the thoracic cavity, containing the heart and lungs, from the abdominal cavity and performs an important function in respiration: as the diaphragm contracts, the volume of the thoracic cavity increases, a negative vacuum is created which draws air into the lungs.


The laboratory rat is one of the most popular experimental models for the experimental surgery of the (human) liver. The objective of this study was to investigate the morphometric parameters, physiological data, differences in configuration of liver lobes, biliary system, and vasculature (arteries, veins, and lymphatic vessels) of the liver in laboratory rats. In addition, this study supports the anatomic literature and identified similarities and differences with human and other mammals.


The stomach is located in close proximity to the abdominal side of the diaphragm. As part of the gastrointestinal tract, on the oral side it is connected to the esophagus at the gastroesophageal junction. This tract is continued into the duodenum at the pyloric ring.

Abdominal fat

the fat distribution in rats is very specific. this is one of the places the fat is found.

Small intestines

The small intestine or small bowel is an organ in the gastrointestinal tract where most of the end absorption of nutrients and minerals from food takes place. It lies between the stomach and large intestine, and receives bile and pancreatic juice through the pancreatic duct to aid in digestion.


The mesenterium is a contiguous set of tissues that attaches the intestines to the posterior abdominal wall and is formed by the double fold of peritoneum. It helps in storing fat and allowing blood vessels, lymphatics, and nerves to supply the intestines, among other functions.


The cecum is a large, thin-walled, blind pouch shaped somewhat like a comma. It is lightly constricted about its middle. The rat cecum differs from that of many other rodents; it is devoid of internal septa. Even though the cecum is not divided into septa or cells, it is subdivided into an apical and a basal part. The basal part contains no lymphoid tissue. The apical portion, on the other hand, contains a distinct mass of lymphoid tissue in its lateral wall. This is thought to be analogous with the vermiform appendix of man.


The rectum is the final straight portion of the large intestine in humans, rats and some other mammals, and the gut in others.