On or about the pericardium.
References in periodicals archive ?
During closure of the cervical sinus that lies between the second branchial arch and the epipericardial ridge, ectoderm may become trapped, resulting in the formation of an inclusion or cyst.
Electron microscopic studies of the normal parietal pericardium show that the tissue is composed of 3 layers: 1) the serosa, consisting of a surface layer of mesothelial cells and a narrow submesothelial space, 2) the fibrosa, containing variously oriented layers of collagen fibrils and small elastic fibers, and 3) the epipericardial connective tissue, containing mainly large coarse bundles of collagen and forming part of the pericardiosternal ligament (4).