I would like to recall that in 1957 Selby noted in thin sections of mammalian epidermis (Selby 1957) granules smaller than the keratohyalin granules. In subsequent studies these granules, called membrane-coating granules (MCG), were shown to migrate toward the plasma membrane and discharge their lammelar content into the intercellular spaces (Matoltsy and Parakkal 1965). The lamellae which spread over the surface of granular cells have been noted to reassemble into bileaflets and to form broad sheets in the intercellular spaces of the horny layer (Matoltsy 1976) as illustrated in Fig. 1. Since histochemical studies have indicated the presence of lipids in MCG-s (Breathnach and Wyllie 1966; Hashimoto 1971), and tracer studies (Elias and Friend 1975; Squier and Hopps 1976) have revealed that ferratin, lanthanum, ruthenium red and horseradish peroxidase do not pass through the horny layer it is reasonable to postulate that lipids derived from MCG-s form an important part of the defence system of the mammalian epidermis and control the flow of hydrophilic substances across the stratum corneum.