170 LABORATORY MANUAL FOR VERTEBRATE ANATOMY 



being designated the gastrosplenic ligament. The lung is also attached to the 

 mesogaster by a short mesentery. That part of the dorsal mesentery supporting 

 the small intestine is the mesentery, in the limited sense; that part supporting 

 the large intestine is the mesorectum. 



The -ventral mesentery is present only in the region of the liver and urinary 

 bladder. One part of it forms the long mesentery extending between the median 

 ventral line of the body wall and the median line of the ventral face of the liver. 

 This is the falciform ligament of the liver. It contains a number of blood vessels 

 which pass from the ventral body wall into the substance of the liver (where 

 they join the hepatic portal vein) . In the free posterior margin of the falciform 

 ligament the ventral abdominal vein crosses from the body wall to the liver. 

 On raising the liver the gastrohepatic ligament will be seen extending from the 

 anterior part of the stomach to the dorsal face of the liver. In the region of the 

 pancreas the hepatoduodenal ligament joins the duodenum and liver and incloses 

 the greater part of the pancreas. The tails of the pancreas, however, are sit- 

 uated in the mesentery of the small intestine. Both of the ligaments just 

 mentioned are parts of the ventral mesentery. The last part of this mesentery 

 is found extending from the urinary bladder to the midventral line of the body 

 wall; this is the median ligament of the bladder. 



Each gonad has a mesentery: mesovarium in the female, mesorchium in the 

 male. The mesentery of the oviduct is the mesotubarium. These should be 

 located by lifting up the structures in question. 



The falciform ligament should now be severed without, however, cutting 

 through the ventral abdominal vein. The numerous lobes of the liver appearing 

 as scallops of the margin may now be seen more clearly. On raising the right 

 side of the liver, the right lung may be identified dorsal to it. Is it of the same 

 length as the left lung ? The small gall bladder will be seen on the dorsal surface 

 of the right side of the liver. Its duct surrounded by pancreas tissue may be 

 readily traced to the duodenum. The pancreas is said to open into the duode- 

 num by a number of fine ducts. 



The anterior end of the pleuroperitoneal cavity is closed by a membrane, 

 the transverse septum. The liver is attached to this by the coronary ligament, 

 which is continuous posteriorly with the falciform ligament. The mode of forma- 

 tion of the septum and the coronary ligament was described in connection with 

 the dogfish. 



3. The pericardial cavity. Make a median ventral incision through the 

 skin from the level of the fore limbs forward to the level of the gills. Remove 

 the underlying muscles bit by bit until you have exposed a membrane, the 

 parietal pericardium. Cut through this membrane. The pericardial cavity in 

 which the heart is situated is thus exposed. Widen the opening into the cavity 

 by cutting laterally along the anterior margin of the pectoral girdle. The 

 muscles between the pericardial cavity and the fore limbs may also be split. 



