Studies On The Microvasculature Of Infant And Adult Yak's Heart

The microvasculature of twelve infant and adult yak′s hearts was observed by scanning electron microscope and optical microscope,measured the diameter of different microvasculature and the density of the capillaries in three layers of the ventricular myocardium firstly by using MoticImages Advanced 3.0,and these vessels in infant yak′s heart have been compared with adult yak′s heart .By these means we have measured that average diameter of the arterioles ,precapillary arterioles,capillary in infant and adult yak′s hearts are73.50μm, 78.50μm ;13.20±2.35μm ,16.24±2.27μm ; 8.57±1.29μm , 6.57±2.28μm,respevtively ;and that the range of these microvasculature are 11.53～100μm ,12.5～100μm; 11.53～15.49μm,12.50～19.99μm; 2.75～11.53μm , 1.25～12.50μm,respectively. The arterioles of yak′s hearts always give rise to capillary after 3-4 grades of embranchmentands,whose diameter of these grades in infant and adult yaks are 85.66±4.53μm, 63.69±6.21μm, 44.38±5.90μm, 35.45±6.17μm; 87.64±4.87μm, 69.46±6.67μm, 48.52±5.77μm, 30.45±5.44μm,respevtively,and whose range are 75.53～90μm, 57.35～75.53μm, 36.51～57.35μm, 15.49～36.51μm; 79.55～95μm, 59.31～79.55μm, 37.50～59.31μm, 19.99～37.50μm,respevtively. The density of capillary of infant and adult yak′s hearts in epicardium, myocardium and endocardium are 1674±243n/mm2,2407±328n/mm2,1489±337n/ mm2;1864±179n/mm2, 528±263n/mm2, 1636±235n / mm2.Arterioles of yak′s hearts were characterized by the bark-like structure and impressions of endothelial cell nuclei . The precapillary arteriole in adult yak′s heart a distinctive cone-shaped appearance.but it is not notable in infant yak.at this level it was found some constrictions generally competed encircled the luminal cast.The outer surface of capillaries cast in infant yak′s hearts are smooth ,and no constrictions,but it is different from infant yak that capillaries in adult yak′s hearts always have some constrictions.in additon, capillaries in myocardium are in parallel with each other, but it is not similar to the capillaries in endocardium and epicardium ,whose arrangement are not regular.and the types of capillary anastomosis of"H"and"Y"are found frequently in the myocardium of yak. The diameter of infant yak′s venules which is less than 500μm are more bigger than that of in adult,which is less than 300μm .the characteristic of infant yak's venules is"baggy"or"bulgy"arrangement. but it is root- like pattern in adult yak′s venules.