Morphofunctional aspects of the myocardicsheath in the cranial vena cava of the bovine (Bos indicus)

ABSTRACT

Data about the functional valve structure of the cranial vena cava in the right atrium of bovines are scarce. We have done a histological study in ten bovines to observe the functional architecture of the conective-muscular wall of the cranial vena cava. After fixation, the intrapericardiac segment was harvested and embedded in paraplast. Transverse and longitudinal sections, which were stained by Masson's Trichromic, Mallory Hematoxylin, Cloridic Orcein and Calleja methods were obtained. We have observed cardiac muscular fibers comming from the atrial musculature. We believe that, during the atrial systole, the contraction of the cardiac muscular fibers, like a spiral, reduces the venous length and increase its diameter, resulting in the blood push into the atrial chamber.