MORPHOLOGICAL ANALYSIS OF THE FISH HEART VENTRICLE - MYOCARDIAL AND CONNECTIVE-TISSUE ARCHITECTURE IN TELEOST SPECIES

Light and scanning electron microscopy were used to study the structur e of the heart ventricle in three species of marine teleost fishes: th e hake (Merluccius merluccius), the angler fish (Lophius piscatorius) and the sea bream (Pagellus centrodontus). Our findings show the ventr icle to be shaped differently in each species: tubular in the hake, sa ccular in the angler fish and pyramidal in the sea bream. From a struc tural viewpoint, interest was centered on two aspects: organization of the myocardial fibres and arrangement of connective tissue. In hake a nd angler fish ventricles, the myocardium was exclusively trabecular i n nature, whereas the bream ventricle, in addition to trabecular myoca rdium, presented a thin compact layer. Muscle fibres showed precise pa tterns of organization at the level of the ventricular orifices. With the techniques used the intramyocardial connective tissue was detected in the following ventricular zones: i) at the level of subepicardial and subendocardial spaces, ii) surrounding the myocardial fascicles, a nd iii) surrounding individual myocardial cells. According to this str uctural study, the pyramidal ventricle of the fish should be considere d as a ventricular pump with greater efficiency.