Gross and microanatomical studies on the moderator bands (septomarginal trabecula) in the heart of mature Dromedary camel (Camelus dromedarius)

Wael Ghonimi,Mohamed Bareedy,Ahmad Abuelatta,Ahmad Balah

doi:10.5455/javar.v1i2p24-31

Abstract

The current work was carried out to investigate the gross and microanatomical features of moderator bands (septomarginal trabecula) in camel heart. Ten hearts were collected from healthy mature dromedary camels. Anatomically, the moderator bands were present in both right and left ventricles. In right ventricle, the walls had one muscular moderator band which was extended from the interventricular septum to the opposite ventricular wall especially to the papillary muscle. In left ventricle, there were two bands; one extended from the interventricular septum to the papillary muscles, and the other one was present in various places especially in the apex running as a thin thread-like band across the left ventricular wall. Histological examination revealed that the moderator band consisted of two major layers; the central (core) myocardium and the peripheral endocardium, acting as band capsule. The myocardium had two bundles; the contractile cardiac muscle bundles and the Purkinje fiber bundles. The endocardium consisted of three layers; the endothelial layer of simple squamous epithelium, the subendothelial layer of loose connective tissue and the subendocardial layer, connecting the endocardium with the myocardium.

Highlights

Moderator bands are fibromuscular structures crossing the ventricular cavities without being attached to the cusps (Cocchieri and Bardelli, 1992)
The moderator band was a single or branched fibromuscular strand that extended from the interventricular septum to the opposite ventricular free wall at the papillary muscle, passing through the ventricular cavity and appeared as fleshy and muscular in its consistency (Figure 1A, B, C)
The walls had one muscular moderator band; ventricular septum which extended from the interventricular septum to the opposite ventricular wall especially at the papillary muscle (Figure 1B, C)

Summary

Introduction

Moderator bands (septomarginal trabecula) are fibromuscular structures crossing the ventricular cavities without being attached to the cusps (Cocchieri and Bardelli, 1992). Crick et al (1998) reported the presence/location of moderator bands in both ventricles of the pig’s heart. Rocha et al (2010) have shown that the muscle bundle in the septomarginal trabecula of pig heart is generally a resistant crest that goes from the lower part of the septum to the lower part of the anterior papillary muscle. Sathyamoorthy and Ramesh (2008) claimed the moderator band for being composed of an outer thick endocardial covering, Purkinje fibers, ordinary myocardial fibers, blood vessels and nerves. The Purkinje fibers were large, irregular cells with centrally placed nuclei. It was present either in the myocardium or in the subendocardium

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Conclusion