The study of extracutaneous cells producing and storing melanin is of interest because it
may provide valuable information about the presence of neural crest elements in internal
organs and tissues. Here we report, for the first time, the presence and distribution of
melanophores in the heart of a chondrichthyan species, the rabbitfish, Chimaera
monstrosa. Pigment cells were found in all of 20 hearts examined. Pigment cells occur
mainly in the cardiac outflow tract, which consists of two anatomical components, the
proximal, myocardial conus arteriosus and the distal, non-myocardial bulbus arteriosus.
A few groups of dark pigmented cells were found in the apex of the ventricle of one
specimen and in the atrium of two specimens. In all instances, the melanophores were
located in the subepicardial space, where they could be well recognized in both
unstained and stained histological sections. The distribution and intensity of the
pigmentation in the cardiac outflow tract varies markedly between individuals. In all
cases, however, the pigmented area is larger on the dorsal than on the ventral surface.
Dorsally, the size of the pigmented area ranges from a fringe that includes the bulbus
and the distal part of the conus to the whole surface of the outflow tract. Ventrally, the
pigmented area does not cover the entire conus arteriosus. The intensity of the
pigmentation also varies widely; in general, it is highest at the distal portion of the conus.
There is no relationship between the distribution and intensity of the pigmentation and
the sex and age of the animals. The functional role of the pigmented cells is unknown. If
the melanophores in the heart of C. monstrosa are indeed of neural crest origin, it would
suggest a notable contribution of the neural crest cells to the cardiac outflow tract in
holocephalans.
Buscar en Dimension