Anatomical Structure Of Ovine Portal Vein And Application Of Fistula Technique

The liver is the viscera that gives priority to metabolism function in the body.The portal vein collects blood from the intraperitoneal organs and the digestive tract to the liver.Portal vein blood is rich in nutrients and is the functional blood vessel of the liver.Portal venous fistula plays an important role in the study of nutrient metabolism and liver targeted drug therapy.In this study,sheep were used as the experimental subjects to explore the anatomical structure of the portal vein and its branch vessels,establish the surgical technique of portal vein fistula in sheep,and analyze the effects of feeding calcium and phosphorus preparations on blood calcium and phosphorus levels by using portal vein fistula technology,in order to provide anatomical and fistula technical support for the related research on nutrition metabolism in ruminants.(1)An autopsy study of 4 adult sheep showed that the portal vein collected blood from the pancreatic vein,gallbladder vein,left gastric vein,anterior mesenteric vein and retromesenteric vein;The left gastric vein collects the venous blood of each compound stomach branch.The anterior mesenteric vein collects mainly venous blood from the small intestine,while the posterior mesenteric vein collects mainly venous blood from the large intestine.The length and outer diameter of the portal vein and its subsidiary vessels were measured with a vernier caliper.The portal vein was 7.8 ± 1.6mm in length and 13.0 ± 2.1mm in outer diameter from the hilar hepatis to the trunk without fork.The outer diameter of the left gastric vein was 83.0 ± 11.0 mm.The outer diameters of anterior and posterior mesenteric veins were 10.0 ± 0.8mm and 5.0 ± 0.4mm,respectively.(2)According to the conventional laparotomy,the lambs were opened at the posterior edge of the last rib on the right side of the sheep.The exposed portal vein near the hilar lymph node was intubated to the liver at a distance of 3 ～ 4 cm from the hilar liver.The operation line was fixed to the hilar lymph node,and 10 U/m L heparin sodium normal saline was used to prevent the fistula from being blocked due to coagulation.The extracorporeal site of the fistula is derived from above the final costal arch near the spine and is fixed to the skin.The fistula can last for about 25 days,and the animal survival rate is 100%.(3)In order to monitor the effect of feeding high doses of calcium and phosphorus on the calcium and phosphorus levels of animals,sheep were fed with calcium dihydrogen phosphate,calcium gluconate and calcium carbonate twice as much as the dietary calcium supplementation,and the portal vein blood was collected dynamically by using the established fistula technology to detect the calcium and phosphorus levels.The results showed that there was no significant difference in serum calcium level in the monitored 9 h after feeding the three calcium and phosphorus preparations compared with that before feeding(P > 0.05),but the serum phosphorus level after feeding the calcium dihydrogen phosphate was extremely significant(P < 0.01)and significantly(P < 0.05)higher than that before feeding at 1.5 h and 2.5 h,respectively.However,there was no significant difference in serum calcium and phosphorus levels between portal vein and jugular vein at the same time point(P>0.05).