The tunica media of the thoracic duct contains a heterogeneous population of muscle cells.
The three-dimensional cyto-architecture and ultrastructure of cells composing the different regions of the tunica media of canine and feline thoracic ducts (ThD) were investigated by scanning and transmission electron microscopy. The tunica media of the intervalvular regions consists of 2-4 layers of circulatory oriented ribbon-like smooth muscle cells (SMCs) of the contractile phenotype. Spot-like membrane contacts similar to gap junctions were observed between SMCs. In the parietal part of the valve's sinus (PPVS), modified SMCs containing large lipid droplets were found. Occasionally, in the upper thoracic part of the ThD in the PPVS, we observed cardiomyocyte-like cells (CMLCs) arranged as circularly oriented bundles. Frequent interdigitation contacts were formed between SMCs and CMLCs, suggesting a possible involvement of the latter cell type in pacemakers activity in the ThD.
Bannykh
S
S
Laboratory of Electron Microscopy, Ivanovo State Medical Institute, Russia.
Bannykh
G
G
Mironov
A
A
D000818:Animals; D002415:Cats; D002462:Cell Membrane / Q000648:ultrastructure; D003593:Cytoplasm / Q000648:ultrastructure; D004285:Dogs; D017629:Gap Junctions / Q000648:ultrastructure; D017348:Microscopy, Electron, Scanning Transmission; D009130:Muscle, Smooth / Q000648:ultrastructure*; D013897:Thoracic Duct / Q000648:ultrastructure*; D017540:Tunica Media / Q000648:ultrastructure*