Corneodesmosomes (CDS) are an ultrastructurally modified form of desmosomes (DS) (Chapman & Walsh 1990). When DS are transformed into CDS between the stratum granulosum and the stratum corneum, the desmoglea loses its trilamellar structure and becomes homogeneously electron dense. On the cytoplasmic side, the attachment plaque (desmosomal plaque) becomes incorporated into the cornified cell envelope (CE). Keratin filaments are connected to the attachment plaque in DS; this association is no longer visible in CDS.
Like DS, desmoglein and desmocollin constitute the extracellular parts of CDS (Simon et al. 1997), but there is an additional unique extracellular component known as corneodesmosin (CDSN). CDSN is a 52- to 56-kDa glycoprotein produced by keratinocytes that is incorporated into the desmoglea of DS shortly before their transformation into CDS during cornification (Serre et al. 1991). It is stored and secreted by Lamellar bodies. After secretion CDSN localizes to the extracellular structures of CDS and covalently cross-links to the CE. This step coincides with the morphological transformation of DS into CDS. In vitro studies suggest that CDSN mediates homophilic binding to counterparts on adjacent corneocytes (Ishida-Yamamoto & Kishibe 2011). Cleavage of desmoglein, desmocollin and CDSN is a key step in desquamation.