gall bladder 

 led pericardium 



ng 



nterior chamber of stomaci 

 iver 



ventral mesentery ^- 



bladder 



phoid anterior port of kidnc 

 posterior end of stomach 



gut 



\~:1 — kidney 



^ventral mesentery 



spleen 



terior expansion of stomach ,' 



(dashed lines' 



gall bladder 



ventral pancreatic duct 

 dorsal pancreatic duct 



pancreas (encircles right side 

 of anterior end of intestine) 



trachea (around right 



side of esophagus) 



liver (closely bound 



to stomach) 



spleen (largely in 

 right wall of stomach) 



bile duct^J 



right kidney 



cloacal aperture 



B 



Figure 9-12. The viscera of Protopterus, a lungfish. A, ventral view of anterior organs; B, lateral 

 view of digestive tract with left wall cut away to show interior (orrow indicates course of lumen); 

 C, dorsal view of anterior organs. 



beginning anteriorly near the opening of the bile duct (dor- 

 sally) and making about six and a half turns in a counter- 

 clockwise direction as it progresses posteriorly. It ends a short 

 distance from the cloacal aperture attached to the ventral 

 wall. Behind the valve is a short section of gut which opens 

 into the cloaca. The cloaca extends upward to the urogeni- 

 tal papilla and then forward, above and parallel to the gut 

 as a blind-ending bladder. The cloacal aperture is to the left 

 of the median fin. 



The liver is a single mass lying ventral and to the right of 

 the stomach. It extends back to a rounded point on the right 

 side. The gall bladder is large and lies in an embayment in 

 the left-hand margin of the liver. The bile duct enters the gut 

 on its ventral aspect just posterior to the gall bladder. The 



pancreas lies within the wall of the gut, beginning to the 

 right of the entrance of the bile duct. Here there is a dis- 

 tinct mass which extends around the right side of the gut to 

 the dorsolateral aspect, where it spreads out as a broad dor- 

 sal lobe. This lobe, still within the wall of the gut, extends 

 back some distance and tapers to a rounded point. This 

 dorsal portion is drained by a duct entering the dorsal mid- 

 line of the gut at the point of the V formed by the pyloric 

 valve. 



The spleen is a large vascular mass in the right dorsolat- 

 eral wall of the stomach. Posteriorly it connects with the 

 pancreas and from here extends forward, tapering all the 

 time to a point just below the anterior joined area of the 

 lungs. A ventral mesentery attaches most of the posterior 



THE DIGESTIVE TRACT AND ASSOCIATED STRUCTURES • 265 



