The Cardiac Septomarginal Trabecula in Man and Some Mammals

Abstract

The present work was designed to describe, in detail, the anatomy, morphometry and minute structure of the septomarginal trabecula of the right ventricle in man and some animals like camel, sheep and monkey. The results of this study would help to highlight the function(s) of such a band in these species. Furthermore, the full description of this trabecula in such animals might hopefully be of some value not only for academic comparative researches but also for the expectancy of utilization of any of them, in the future, in human cardiac reconstructive surgeries. Forty adult hearts, of both sexes, (10 for each species) were used in this investigation for the comparative morphological, morphometric and light microscopic study of the septomarginal trabecular (moderator band) in man, Arabian camel, sheep and monkey. This work was carried out in the Anatomy and Histology Laboratories, College of Medicine, KFU, Dammam, KSA. The trabecula was grossly examined and morphometrically assessed. Histological sections of the trabecula were differently stained and examined by the light microscope. The trabecula was observed to extend from the interventricular septum to the base of the anterior papillary muscle in man (or the muscle papillaris magnus in animals). In each of the four species investigated, the trabecula carried the specialized myocytes of the conducting right bundle branch that appeared as a longitudinal fibrocellular tract amongst ordinary myocardial fibres. The cells of this tract were faintly stained, foamy, arranged edge to edge in clusters, displaying a mosaic-like appearance, and increasing in size as traced distally. The minute structure of the trabecula was observed to be the most developed in sheep and the least in monkey. A tortuous small-sized artery was detected within the trabecula. No morphological or structural sex-differences of the trabecula existed in any of the species investigated. Some significant morphometric species-differences were detected