Membrane structure of the cells of the lamprey notochord
Bartels, H. and Potter, I.C. (1998) Membrane structure of the cells of the lamprey notochord. Journal of Electron Microscopy, 47 (6). pp. 627-636.
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Thin-section and freeze-fracture electron microscopy have been used to determine the types of junctions that are present in the notochord of adult lampreys and thereby propose ways in which the functional properties of the notochord are integrated. The notochord consists of a fibrous sheath, which surrounds a single layer of small 'epithelial' cells and a central core of large vacuolated cells. The epithelial and vacuolated notochordal cells are all linked by numerous desmosomes, which are the predominant type of intercellular junction in the notochord. Furthermore, the notochordal epithelium is linked to the inner surface of the notochordal sheath by many hemidesmosomes, which are associated with patches of basal lamina-like material. The above linkages, produced by desmosomes and hemidesmosomes, together with the tensile strength of the notochordal sheath, must be crucial for maintaining the structural integrity of the notochord during the sinuous swimming movements exhibited by lampreys. The communicating (gap) junctions, that are present between vacuolated cells, would facilitate metabolic coupling between these cells. Zonulae occludentes ('tight junctions') were not found between notochordal epithelial cells, indicating that there is no effective paracellular barrier to the diffusion of macro-molecules, ions and small polar solutes at the outermost layer of the notochordal cells.
|Publication Type:||Journal Article|
|Murdoch Affiliation:||School of Environmental and Life Sciences|
|Publisher:||Japanese Society for Microscopy|
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