Morphological Study on Microvasculature of Left Ventricular Wall in Infant and Adult Yaks

Abstract

Observations on the microvasculature in the left ventricular wall of infant and adult yaks under light and scanning electron microscope (SEM) were presented. Moreover, the diameter of different microvasculature and the density of the capillaries in three layers of the ventricular myocardium were measured using Image Pro-Plus 5.0. The results showed that the average luminal diameter of arterioles and precapillary arterioles in adult yak's hearts were, in most cases, larger than those in infant yaks. On the contrary, the diameters of the capillary in infant yak's hearts were larger than those in adult yaks. The density of capillary in the myocardium of adult yak's heart had significantly higher values (P<0.01) than those in infant yaks. Arterioles of yak's hearts were characterized by the bark-like structure and the impressions of endothelial cell nuclei, and it always gave rise to capillary after three to four grades of embranchment. The outer surface of capillaries cast in infant yak's hearts was smooth, and no constrictions were found. This was different from adult yak that always had some constrictions. The capillary anastomosis of ''H'' and ''Y'' usually existed in the myocardium of both adult and infant yaks; however, those in infant yaks were not typical as in adult yaks in their shape. The peculiar arrangement of the venules in infant yak was a ''baggy'' or ''bulgy'' arrangement, while in the adult yak, they had a root-like pattern. Our findings suggest that the patterns of microvasculature in yak's heart could be propitious to adapt better in their environment following their increase of age. Anat Rec, 293:1519Rec, 293: -1526

Comparative Quantitative Studies on the Microvasculature of the Heart of a Highly Selected Meat-Type and a Wild-Type Turkey Line

“…Michel et al [26] reported a relationship of 1 capillary to 4 cardiomyocytes in domestic chickens, 1:6 in domestic ducks and 1:9 in pheasants. In the mammalian heart the number of capillaries per mm 2 was reported as about 2000–4000 in the human [27, 28] and rat [29, 30], 5000 capillaries in sheep [31] and 2500 in the Yak [32]. These results indicate the large range of these allied parameters among different species.…”

Changes in the Anatomic and Microscopic Structure and the Expression of HIF-1α and VEGF of the Yak Heart with Aging and Hypoxia

“…Previously, it was found that the microvasculature and conduction system of the yak heart has unique characteristics [ 20 , 21 ], suggesting that the vasculature of the yak heart constructs an adaptive structure to cope with the low-oxygen situation. However, there is a little information on the levels of protein expression of HIF-1α and VEGF following the birth of yaks, and during their maturation at high altitude.…”

Are the precapillary sphincters and metarterioles universal components of the microcirculation? An historical review

“…Six of the studies described precapillary sphincters, two employing TEM [60, 61] and four employing SEM-vc [62–66]. In the other studies, the existence of precapillary sphincters was neither mentioned in the text nor demonstrated in the figures; in some studies their absence was concluded.…”

“…Anderson and Anderson reported an indication of precapillary sphincters in dog heart with SEM-vc [63], but the abrupt interruption and irregular shape of the vascular casts indicated that the resin did not sufficiently fill the vascular lumina so that the identification of precapillary sphincters was not based on sound evidence. He et al [66] reported step-wise constriction of arterioles in yaks and interpreted this as the precapillary sphincters being distributed in a certain section of the arterioles. These structures were far from the precapillary sphincters branching into capillaries reported in the physiological studies.…”