Ultrastructure
and 3D morphology of cells within cancer microspheres.
(A) SEM image of MCF7 microspheres reveals dense local colony formation
in individual microspheres. (B) At higher magnification, MCF7 cells
appear to be tightly packed within individual colonies with visible
cell-surface microvillus-like features. (C) SEM image of MDA-MB-231
microspheres and (D) higher magnification image revealing individual
cells (bulge-like appearance) interacting with the surrounding PF
hydrogel matrix. (A,C: scale bar = 100 μm; B,D: scale bar =
10 μm). Microspheres appear smaller in size due to the shrinkage
effects of SEM sample preparation. (E–H) Confocal z-projection
of MCF7 and MDA-MB-231 cells reveals prominent cell-type-dependent
differences in proliferation and 3D morphology (green: Ki67, red:
F-actin, blue: nuclei; scale bar = 200 μm). All images were
obtained on day 14 of culture.