Nanostructure of the epidermal extracellular space as observed by cryo-electron microscopy of vitreous sections of human skin

The newly developed method, cryo-electron microscopy of vitreous sections, was used to observe the nanostructure of the epidermal extracellular space. The data were obtained from vitreous sections of freshly taken, fully hydrated, non-cryo-protected human skin. The extracellular space of viable epidermis contains desmosomes, expressing a characteristic extracellular transverse similar to 5 nm periodicity, interconnected by a relatively electron lucent inter-desmosomal space. The extracellular space between viable and cornified epidermis contains transition desmosomes at different stages of reorganization interconnected by widened areas expressing a rich variety of complex membrane-like structures. The extracellular space of cornified epidermis contains similar to 9, similar to 14, similar to 25, similar to 33, similar to 39, similar to 44, and similar to 48 nm thick regions in turn containing one, two, four, six, eight, eight, and ten parallel electron-dense lines, respectively, between adjacent corneocyte lipid envelopes. The eight-line similar to 44 nm thick regions are most prevalent.