Anatomic And Histological Study In Wuzhishan Inbreeding Minipig And Detection Of Porcine Endogenous Retrovirus (PERV)

Wuzhishan pig is one of the specific local swine species and originally distributed in the remote mountain area of Hainan Province in south China.At present,we had gained minipig group with 0.979 inbreeding coefficient and 30kg-35kg mature body-weight by inbreeding after introduced to the Institute of Animal Sciences in Beijing from 80s,19^th century.Wuzhishan minipig inbred line with much merit such as dwarf body type,stabile heritage and high degree inbreeding is extensively applied to different study domain in biomedical,and becoming ideal animal model about the study of human disease,and included as preferred swine species of organ transplantation in China.However,in recent years,the researches discovered that PERV can infect human cell in vitro,which produced doubt to safe of xenotransplantion from pig to human,so it is becoming important that sieving PERV-free minipig for xenotransplantion.In this study,inbred F16 Wuzhishan minipigs were selected as experimental animal to observe anatomical structure of digestive system,urinary system and heart,microstructure and ultrastructure of the heart,liver,kidney,immune system and partial Growth-Axis organs,and detected expression of PERV-RNA in 15 kinds of tissues.Main results were as follows:1 Anatomical study of heart,digestive and urinary organs in Wuzhishan minipig inbred lineThe anatomic feature of heart,digestive and urinary organs were observed by gross anatomical means in Wuzhishan minipig inbred line,the result showed that development of premolar teeth were later,the stomach was "V"-shape in appearance,the small and large intestine were shorter than other swine species,the liver was ladder-shaped with vaulted angle.Anterior extremity of kidney was blunter than posterior extremity that was distant with median line of body,there are two renal arteries in the partial Wuzhishan minipigs,and the bladder with unsharp vesical triangle.The cardiac broad diameter was conspicuously increased from 2 to 12-months old,the crista terminalis were not conspicuous between right auricle and sinus of venae cavae,the azygos vein was directly opened at the open of coronary sinus.Compared to human,the foliate papillae of tongue were not conspicuous,the calciform papillae were less,the distance between cardia and pylorus was closer in stomach,the jejunum and ileum were longer,the appendix was grosser,colon formed colon-cone.The gross morphous and location of kidney and bladder were similar to the human,but the morphous of liver and pancreas were markedly different with the human.The weight and volume of heart in 12-months old Wuzhishan minipig were less than adult,and left and right pulmonary vein were small,and anterior and posterior vena cava were same.The construction features indicated that the digestive system was markedly different with the human in gross anatomy,which was unsuitable for application of xenotransplantion except the heart and kidney.2 Histological observation of immune organ in Wuzhishan minipig inbred lineThe histological characteristics of immune organs were observed by paraffin section and HE staining,to provide basic morphology data for WZS minipig inbred line,it will be used to established animal model of immunologically disease about human.The results showed that thymus corpuscles,dividing and mature thymocyte were gradually increased in thymus substance from birth to sexual mature.The thymocyte were gradually decreased and loosely disposed,the thymus corpuscles and thymic epithelial cell were also decreased in adult.There were many different-sized bulliform cells and deformed cell debris in periphery of the thymus corpuscle in 2-months-old pigs.Before 4-months-old,the periarterial lymphatic sheath and splenic corpuscle were increased as growth in splenic white pulp,but the gentle reduction and retention on invariably level in 12-months-old pigs,those changes were identical to rat and fowl on the whole.There were indistinct limitation between lymphoid node cortex and medulla in 4-months-old, but in 2-months-old,the cortex was in interior of lymphonode substance,the medulla was in exterior.Compared to 2 and 4-months-old,the lymph nodule was larger,and the lymphocyte were loosely disposed in the cortex,the lymphocyte were less,and blood capillaries were gradually increased in 12-months-old pigs.The histological structure of immune organ were similar to that of human and other mammal on the whole.3 Microstructural and ultrastructural study of heart,liver and kidney in Wuzhishan minipig inbred lineThe transplantatation of heart,liver and kidney is very important role in homotransplantations and xenotransplantation,so it is significant to study construction features of those organs for application of transplantation.The morphological characteristics of heart,liver and kidney were observed by microhistological and ultramicrohistological skills in Wuzhishan minipig inbred line,the results showed that development of many organs were immature in 2-months-old pigs,with clear construction features in 4-months-old pigs.But from general observation,the histological structure of ventricular wall,liver and kidney and the ultrastructure of ventricular muscle, liver and cortex of kidney were very similar to human in 12-months-old pigs,so whom is fit donator for the xenotransplantation.4 Morphological study of hypophysis,thyroid and pancreas in Wuzhishan minipig inbred lineThe hypophysis is located in tectonic hypophyseal fossa,anterior pituitary encase posterior pituitary,pituitary pars intermedia is narrow with unsharp follicle structure, secretary granule is the largest in gonadotroph and the smallest in ACTH cell than other endocrine cell in the anterior pituitary,the secretory granule of neuraxon are less and the Herring body is not obvious in the posterior pituitary.Thyroid follicle is gradually becoming large with growth,microvilli of follicular epithelial cells are undeveloped. There are two kinds of ultimobranchial cells with high or low electron density.Pancreas gland alveolus are tightly disposed with undeveloped connective tissue,there are not connective tissue around pancreatic island,the large and round zymogen granule fill in intracytoplasm of acinous cell with junctional complex on the lateral plane,the cubic centroacinar cell is large,the endothelial cell of blood capillary with cubic nucleus between gland alveolus.Above results indicated that the anatomic,histological and ultrastructure of pituitary,thyroid and pancreas have some discrepancy between human and the Wuzhishan minipig inbred line.5 Detection of PERV in Wuzhishan minipig inbred lineThe expressive status of PERV in Wuzhishan minipig inbred line was detected by RT-PCR,the results showed that the PERV was hardly expressed in heart,and with low expression in liver,kidney and brain.The PERV extensively existed in reproduction and endocrine tissue with high expression in immune tissue,which indicated that there are strong infectivity between the PERV and immune system.