Lamellar inclusions in follicular horny cells: A new aspect of abnormal keratinization

Follicular casts, consisting of horny cells surrounding a core of sebum and bacteria, were removed intact from the pilosebaceous canal of acne patients by means of cyanoacrylate adhesive. When examined at the ultrastructural level, the interior of the follicular horny cell contained highly ordered systems of lamellae and large inclusions of particulate material. Lamellae consisted of 68-Å wide bilayers in immediate opposition with no interlamellar space. These images are indicative of the presence of lipid bilayers most probably composed in part of polar lipids. Lamellae were often contiguous with the large inclusions of particulate material suggestive that they are the same substance sectioned in different planes. These findings indicate that during abnormal keratinization large amounts of polar lipids are retained by the horny cell and utilized not only as components of the plasma membrane, but as matrix constituents.