Establishment of the heart cytoarchitecture: A histological, immunohistochemical, and ultrastructural study in goats (Capra hircus)

Abstract

Goat products carry economic importance worldwide yet relatively little is published about the cardiovascular structure and function in this important animal. Goat hearts have played essential roles as models for human cardiovascular diseases and in artificial heart studies. The present study investigated key structural components within the various layers of the goat ventricle, including the endocardium, myocardium, and epicardium, with particular reference to neuron-specific enolase (NSE) expression. The endothelial lining of the endocardium exhibited strong immunoreactivity to NSE, caveolae of different sizes and short filopodia were observed bulging toward the lumen; and Weibel Palade bodies were present. This study also described the ultrastructural components of the goat myocardium (cardiac muscle), including the Z lines, A bands, I bands, H zones, M zones, the abundant peripheral mitochondria, and the sarcoplasmic reticulum. The Purkinje fibers were peripherally arranged myofibrils and expressed positive immunoreactions to NSE. Telocytes were observed in both the endocardium and myocardium, in close proximity to lymphocytes, mast cells, and cardiac myocytes. The telocytes additionally contained vesicles and abundant amounts of rough endoplasmic reticulum and exhibited positive immunoreactions to NSE. The interstitium, epicardial mesothelium, and fibroblasts were all NSE-positive.