Cytoskeletal elements of STRO-1+ DaMSCs and long-distance cell-to-cell connections (TNTs).

(a,b) Different cell-to-cell connections between STRO-1+ cells. Intercellular connections are able to bridge long distances even across neighbouring cells (Phalloidin/Tubulin staining, merged images). (b) Thick tubes (diameter >0.4 µm, example is marked by red arrow) contain F-actin and α-tubulin, whereas thin tubes (diameter <0.4 µm, example is marked by green arrow) contain only F-actin. (c) Negative control, staining without Tubulin antibody. (d–f) Scanning electron microscope pictures (SEM) of a mixed culture of antlerogenic cells. Cells form long connections across neighbouring cells (d,e) and very high magnification (f) proves that the surface of TNTs exhibit small appendages; long-distance connections are also possible between morphologically distinguishable cell types (d). (h–m) Multichannel pictures of Phalloidin (h,k) and Tubulin (i,l) stained DaMSCs demonstrate that their intercellular connections continuously consist of F-actin but only partially of microtubules. The visible spindle apparatus (i, detail enlargement) point to an initiating cell division and provides evidence that the used α-tubulin antibody is also efficient in DaMSCs. (j,m). Merged Images.