Calotes is a cold blooded (poikilothermic) and terrestrial garden lizard. Pigeon is a ward blooded bird adapted for aerial mode of life. Rabbit is warm blooded and a herbivorous mammal which is also known as Oryctolagus. The circulation of blood in vertebrates is of closed type(circulation occurs is blood vessels. The blood vessels which collect blood from different parts of the body are called as veins. The walls of veins are thick and possess valves.Thier lumen is wide. They collect deoxygenated blood from different parts of the body and carry to the heart. The veins are formed by means of capillaries in the respective tissues or organs. The deoxygenated blood is received by the sinus venosus or the right auricle. The portal veins are having capillaries at their both ends. The pulmonary veins possess oxygenated blood.


lizard(Calotes) - Venous System
1) Sinus Venosus
2) Post-caval
3) Liver
4) Postcaval
5) Gonad
6) Right efferent renal vein
7) Trachea
8) External jugular vein
9) Internal jugular vein
10) Pulmonary vein
11) Ventricle
12) Hepatic vein
13) Stomach
14) Hepatic portal vein
15) Anterior a bdominal vein
16) Gonad
17) Left efferent renal vein •
18) Renal portal vein
19) Femoral vein
20) PeMc vein
21) Caudal vein.



1. The venous system consists of common pulmonary vein, two precaval and one post caval veins. These collect blood from the various parts of the body.

1. The venous system con­sists of three large veins-teeo precavak and one post caval along with four large pulmonary veins.

I. The venous system con­sists of four distinct divisions. i) System of venae carae ii) Hepatic portal system iii) Pulmonary system iv) Coronary system

2. The two precaval veins collect blood from the anterior part of the body. Each precaval is formed by the union of the internal and external jugular veins from head and the sub clavian vein from the arm. Transverse jugular vein is absent. Azygous vein is also absent.

2. The two precaval veins collect blood from the anterior part of the body. Each precaval vein is formed by the union of Jugular (head), brachial (arm) and pectoral (Pectoral muscfes) veins. Transverse jugular vessel is present in between the jugular veins. Azygous vein is absent

2. The two precaval veins collect blood from the anterior part of the body. Each precaval vein is formed by the union of the external jugular vein (head) and subclavian vein (fore limb). The right precaval vein receives the azygous (unpaired) and intercostal veins (intercostal muscles and dorsal wall of theory). Left azygous vein is absent.

3. The post canal vein joins the posterior angle of the sinus venous. It forms by the union right and left efferent renal veins and brings blood from the posterior side.

3. The post caval vein is formed by the union of two large itac veins a tittle behind the liver.

3. The post caval vein is a large median vein. It stands at the cauda region (icaudal vein] and runs forward and receives blood in its course. The veins which join the posl caval vein are pairec ilio himbars, iliacs gonadial renal, anc hepatic.

4. The renal portal system collects blood from the posterior side of the body. Caudal vein bifurcates into two pelvic veins which . unite in front and form into the median anterior abdominal vein enters into the liver. Each pelvic vein joined by femoral, sciatic veins of that side. From the pelvic arise the renal portal veins which branch into capillaries in the substance of the kidneys coccygeo-mesenteric vein is absent.

4. Renal portal system is not well developed in pigeon caudal vein bifurcates into right and left renal portal veins (Hypo gastric veins) each of which enters the kidney. The hypogastric vein receives the Internal iliac vein abng with femoral & sciatic veins. At the bifurcation of the caudal vein into the two renal portal veins arise a median 'coccygeome-senteric vein'. It is characteristic of birds. The coccygeo- mesenteric vein joins the hepatic portal vein.

4. Renal portal system is completely absent in Rabbit.

5. The Hepatic portal vein collects blood from the alimentary canal and enters the liver and breaks upto capillaries.

5. The Hepatic portal vein collects bbod from the alimentary canal and emptied into the liver. From the Ever the blood is carried by the post caval vein through hepatic veins.

5. Same as in pigeon.

6. Epi gastric vein is absent.

6. Epi gastric vein returns the blood from the mesenteries and joins the hepatic veins. This vein corresponds to the abdominal vein of the frog.

6. Epi gastric vein is absent.

7. The right and left pulmonary veins bring pure blood from the right and left lungs and united into a common branch. Common pulmonary vein opens into the left auricle.

7. Four large pulmonary veins return blood from the posterior part of the left auricle

7. A pair of pulmonary veins bring oxygenated blood from the lungs They unite by a common arch and open into the dorsal wall of the left auricle

8. The right auricle receives deoxygenated blood through sinus venosus and left auricle possess oxygenated blood. In the partially divided ventricle the blood mixes to some extent.

8. The right side of the heart (right auricle & ventricle) receives de-oxygenated blood and left side folded with (left auricle & ventricle) oxygenated blood.

8. Same as in pigeon. Coronary veins collect deoxygenated blood from the wall of the heart. The coronary sinus opens into the right auricle through an aperture guarded by the Valve of The besius'. The opening is called as the 'formina of the The besius'.