Marked Changes in Lamellar Granule and Trans-Golgi Network Structure Occur During Epidermal Keratinocyte Differentiation

Epidermal lamellar granules (LGs) transport various lipids, proteins and protein inhibitors from the trans-Golgi network (TGN) to the extracellular space, and play an important role in skin barrier formation. We elucidated the three-dimensional (3D) structure of LGs and the TGN in normal human skin by focused ion beam scanning electron microscopy (FIB-SEM). Reconstructed FIB-SEM 3D images revealed that the overall LG structure changed from vesicular to reticular within the second layer of the stratum granulosum.