Comparison of morphology and microstructural components of hepatic portal vein between human and pig.

In order to provide morphological data and theoretical basis for pig-to-human hepatic xenotransplantation, the difference in morphological parameters and vessel wall structural factors between human and porcine hepatic portal vein was studied. From human subjects and pigs of varying ages, hepatic portal veins were collected, paraffin-embedded and cut into sections. The histological structures were stained with HE, and elastin, collagen and smooth muscles were stained with Weigert, Aniline blue and orange G, respectively. Morphological parameters and relative contents of structural components were determined under microscopy and by computer image analysis system, respectively. The results showed that histological structures of human and porcine hepatic portal vein wall were similar. Caliber, wall thickness, lumen and wall area in pigs increased with age, all in linear correlation to months. Morphological parameters of 6- month-old pigs were similar to those of human. In pigs, collagen content increased gradually with months, elastin content remained relatively stable, smooth muscle content reached the peak at the 3rd month, and collagen/elastin (C/E) rose gradually. The contents of collagen and elastin in porcine hepatic portal vein wall were lower, while the content of smooth muscle was higher than in human, and C/E at the 5th and 6th month was similar to that in human. It is concluded that morphological parameters and contents of structural components of porcine hepatic portal vein vary with age. At the 6 month, its caliber, wall thickness, lumen and wall area are similar to those of human. There are differences in contents of structural components between human and pigs. However, in terms of C/E, mechanic properties of pigs at the 5th and 6th month mimic those of human, hence inosculation is viable in xenotrans-plantation between pigs and human.