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- Title
EPICARDIAL FORMATION IN SITU AND IN CULTURE.
- Authors
Green, Jessica; Crossland, Randy; Langford, J. Kevin
- Abstract
The epicardial layer of the heart was once thought to be derived from the primitive myocardium. Recent evidence demonstrates that it derives from the proepicardium (PE). During the early 1980s, several scanning electron microscopic studies described the migration of the mesothelial cells from villous projections of the PE onto the myocardial surface of the heart, thus creating the epicardial layer and a matrix-filled subepicardial space. Mesenchymal cells, present within the core of the PE, populate this space and give rise to the coronary vasculature of the developing heart. To better understand the growth and migration of these cells during developmental processes, cells derived from the PE have been observed in tissue culture on and within type I collagen lattices. While this is a well accepted model for tissue culture, the current study compares the morphology of epicardial cells in situ with that observed in culture using scanning electron microscopy. Cells present at the leading edge of the enlarging sheet of epicardium in situ displayed numerous filopodia as well as thin ruffling of the plasmalemma. On the surface of the most established area of the epicardium, the classic cobblestone morphology of mesothelial cells was evident. Small surface projections were common at the cellular junctions of these surface cells. In culture, the same cobblestone morphology and short projections were present throughout the epicardial cells. However, few filopodia were present at the edge of the mesothelial sheet in culture. This morphological difference may be due to the different substrates these cells were being challenged to spread upon, (i.e., myocardial cells in situ and type I collagen in culture). Epicardial cells within the confluent sheet likely are spreading on epicardially- derived matrix, similar to that present in the subepicardial space. This study illustrates that, while collagen type I serves as an adhesive and migratory substratum for studying morphological processes, the interpretations must be tempered with the understanding that cells are continually modifying their substratum in culture, as they do in situ.
- Subjects
CARDIOMYOPATHIES; ELECTRON microscopic diagnosis; PERICARDIUM; MESOTHELIUM; HEART diseases; THERAPEUTICS; VASCULAR endothelium; CELL membranes; SCANNING electron microscopy
- Publication
Texas Journal of Microscopy, 2007, Vol 38, Issue 2, p100
- ISSN
1554-0820
- Publication type
Article