Pigmentation of the aortic and pulmonary valves in C57BL/6J x Balb/cByJ hybrid mice of different coat colours.

Neural crest-derived melanocytes have been recorded in several parts of the mammalian heart but not in the pulmonary valve. We report here the presence of melanin-containing cells in the leaflets (cusps) of both the aortic and pulmonary valves. A total of 158 C57BL/6J x Balb/cByJ hybrid mice exhibiting four coat colours, namely black, white, agouti and non-agouti brown, were examined.

The valves of the cardiac outflow tract of the starry ray, Raja asterias (Chondrichthyes; Rajiformes): Anatomical, histological and evolutionary aspects.

The cardiac outflow tract of chondrichthyans is composed of the myocardial conus arteriosus, equipped with valves at its luminal side, and the bulbus arteriosus devoid of myocardium. Knowledge of the histomorphology of the conal valves is scarce despite their importance in preventing blood backflow to the heart. Current information on the subject refers to a single shark species.

The anatomical components of the cardiac outflow tract of chondrichthyans and actinopterygians.

The outflow tract of the fish heart is the segment interposed between the ventricle and the ventral aorta. It holds the valves that prevent blood backflow from the gill vasculature to the ventricle. The anatomical composition, histological structure and evolutionary changes in the fish cardiac outflow tract have been under discussion for nearly two centuries and are still subject to debate.

The arrangement of the coronary artery trunks is subject to inheritance factors: A study in Syrian hamsters.

The concept that anatomical variations in the coronary artery tree might be influenced by genes is relatively old. However, empirical evidence on the effect of genotype on the coronary morphology is still scarce. In the Syrian hamster, there is a septal coronary artery which arises from the left or from the right coronary artery and supplies most of the interventricular septum.

The bulbus arteriosus of the holocephalan heart: gross anatomy, histomorphology, pigmentation, and evolutionary significance.

This study was designed to determine whether the outflow tract of the holocephalan heart is composed of a myocardial conus arteriosus and a non-myocardial bulbus arteriosus, as is the case in elasmobranchs. This is a key issue to verify the hypothesis that these two anatomical components existed from the onset of the jawed vertebrate radiation. The Holocephali are the sister group of the elasmobranchs, sharing with them a common, still unknown Palaeozoic ancestor.