Morphological observations on the mesodermal cells in the 8 day opossum embryo.
Cells of the mesodermal layer of the 8 day opossum were examined by scanning and transmission electron microscopy after removal of the ectoderm. The mesodermal layer is formed by a multilayered network of large somewhat flattened, stellate-shaped cells, whose broad surfaces usually lie parallel to the external surface of the embryo. The mesodermal cells show numerous cytoplasmic processes which often appear as long delicate threads that may branch. The processes may course for considerable distances and establish contact with adjacent mesodermal cells. Contact points between processes, processes and cells, and between adjacent cell bodies showed junctional complexes. Most of the junctional complexes appeared morphologically similar to the nexus (communicating) type. Occasional desmosome-like junctions also were observed. Extracellular fibers were not observed.
D000818:Animals; D003594:Cytoplasmic Granules / Q000648:ultrastructure; D007365:Intercellular Junctions / Q000648:ultrastructure; D008648:Mesoderm / Q000648:ultrastructure*; D008854:Microscopy, Electron; D008855:Microscopy, Electron, Scanning; D009893:Opossums / Q000196:embryology*; D009940:Organoids / Q000648:ultrastructure