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ABSTRACT:
Odland bodies, are small sub-cellular organelles of size 200-300nm.Odland bodies are otherwise known as lamellar bodies, membrane coating granules, lamellar granules and keratinosomes. They are present in the upper spinous and granular cell layers of the epithelium. They are made of glycolipids. They have lamellated internal structure. They are formed near the Golgi apparatus in the cell, migrating to the cytoplasm and discharging its contents into the intercellular space forming the permeability barrier. They act as vital multi-functional constituent of epithelium. They also act as processing and repository areas for lipids that contribute to the epithelial permeability barrier. They contain cathepsin D, kallikrein, proteases and other proteins including corneo-desmosins. Odland bodies play an important role in maintaining homeostasis as they are involved in epithelial permeability barrier function, formation of the cornified envelope, desquamation of keratinocytes, and in local anti-microbial immunity. Recent studies also reveal that they play a role in the local innate immune response as they contain beta 2 defensins, which are anti-microbial peptides with potent activity against candida and Gram-negative bacteria. This article reviews the structure, formation and functions of the Odland bodies.
Key words: Lamellar bodies, stratum granulosum, spinous cells, stratum spinosum.
1. Introduction:
Lamellar bodies also known as Odland bodies, membrane coating granules, keratinosomes, corneocytes and cementosomes are tubular and/or ovoid-shaped membrane -bound secretory organelles of the epidermis. In the initial years of electron microscopy Selby (1957) first observed the lamellar bodies in the stratum granulosum layer of human epidermis but believed it to be small keratohyalin granules[1]. The same structures were also noticed by Horstman (1958) on rat food pad epidermis who interpreted it as virus particles [2]. Odland (1960) on his study found these granules that made their appearance in the upper spinous and lower granulosum layers but disappear in those cells in which keratohyalin granules advance and advocated that these granules were "attenuated mitochondria" [3]. Frei and Sheldon (1961) unlike Odland suggested to refer these granules found on mouse epidermis as "corpuscula "and believed them to be either viral substances or secretory granules[4].Matoltsy and Parakkal (1965) first identified the role of these granules in the formation of permeability barrier that withstand the flow of solutes between the cells of stratum corneum and referred them as "membrane...