title: Skin Lamellar Bodies are not Discrete Vesicles but Part of a Tubuloreticular Network.
abstract: Improved knowledge of the topology of lamellar bodies is a prerequisite for a molecular-level understanding of skin barrier formation, which in turn may provide clues as to the underlying causes of barrier-deficient skin disease. The aim of this study was to examine the key question of continuity vs. discreteness of the lamellar body system using 3 highly specialized and complementary 3-dimensional (3D) electron microscopy methodologies; tomography of vitreous sections (TOVIS), freeze-substitution serial section electron tomography (FS-SET), and focused ion beam scanning electron microscopy (FIB-SEM) tomography. We present here direct evidence that lamellar bodies are not discrete vesicles, but are part of a tubuloreticular membrane network filling out the cytoplasm and being continuous with the plasma membrane of stratum granulosum cells. This implies that skin barrier formation could be regarded as a membrane folding/unfolding process, but not as a lamellar body fusion process.
authors.affiliation: Department of Cell and Molelcular Biology, Karolinska Institutet, 17177 Stockholm, Sweden.
authors.forename: Lianne
authors.initials: L
authors.lastname: den Hollander
authors.forename: HongMei
authors.initials: H
authors.lastname: Han
authors.forename: Matthijs
authors.initials: M
authors.lastname: de Winter
authors.forename: Lennart
authors.initials: L
authors.lastname: Svensson
authors.forename: Sergej
authors.initials: S
authors.lastname: Masich
authors.forename: Bertil
authors.initials: B
authors.lastname: Daneholt
authors.forename: Lars
authors.initials: L
authors.lastname: Norlén
mesh_terms: D000328:Adult; D001706:Biopsy; D002462:Cell Membrane / Q000648:ultrastructure*; D020285:Cryoelectron Microscopy; D022162:Cytoplasmic Vesicles / Q000648:ultrastructure*; D006801:Humans; D021621:Imaging, Three-Dimensional; D008297:Male; D008854:Microscopy, Electron / Q000379:methods*; D008855:Microscopy, Electron, Scanning; D008875:Middle Aged; D012867:Skin / Q000166:cytology / Q000648:ultrastructure*