Occurrence of cardiac muscle in the hepatic portal vein wall of the mouse and rat

Abstract

Cardiac myocytes have been shown to occur in the tunica media and adventitia at the region near the hepatic end of the portal vein of the mouse and rat, and have been studied by electron microscopy in the mouse portal vein. They measured 3-10 microns in breadth at their nuclear level, possessed centrally located nuclei, and were connected with each other by the intercalated disk. In these myocytes in the mouse portal vein, sarcoplasmic reticulum was represented by a rather simple and loose network of the anastomosing tubules. The membrane-bound granules, which closely resemble the atrial specific granules, were found in many of the mouse portal vein myocytes. Transverse tubules, 40-200 nm in diameter, were sometimes detectable at the Z line level. The nexus occupied about 3-5% of the whole junctional area between cardiac myocytes in the tunica media, whereas in the tunica adventitia the corresponding value was about 17%. Blood capillaries with fenestrated endothelium supplied the cardiac myocytes in the adventitia of mouse portal vein. The closest relationship between the adrenergic axon and portal vein cardiac myocytes was observed to be ca. 0.3 micron apart. The significance of these findings is discussed in relation to pulsations of the portal vein.

Murine pulmonary myocardium: Developmental analysis of cardiac gene expression

“…Cardiac-like muscle has been reported within the hepatic portal vein based upon ultrastructural observations (Yokota and Yamauchi, 1985). These cells were of probe by red blood cells within the lumen of the vessel.…”

“…Since the portal vein is derived from a portion of the right vitelline vein, which also drains into the sinus venosus (embryonic vein 3 in Fig. 3C), it is possible that cardiac muscle observed there (Yokota and Yamauchi, 1985) is due to occasional invasion by sinuatrial cardiomyocytes.…”

Structural Organization of Hepatic Portal Vein in Rat with Special Reference to Musculature, Intimal Folds, and Endothelial Cell Alignment

“…Some veins near left or right atrium contain cardiac muscle outside of CSM (Cullinan et al,1986; Endo et al,1994; Endo et al,1997; Hashizume et al,1998; Hosoyamada et al,2010). Yokota and Yamauchi (1985) clearly showed cardiac muscle in the wall of mouse HPV by light and transmission electron microscopy. In that article, they mentioned that cardiac muscle was also associated with a small region of rat HPV; however, they exhibited no micrographs showing cardiac muscle in rat HPV.…”