I. Structures of Epidermal Origin

1. Basement membrane (basal lamina) (primarily of epidermal origin except the lamina reticularis)
   • hemidesmosomes (structures linking the basal keratinocytes to the basement membrane)
   • lamina densa (composed of type IV collagen, the component of the basement membrane between the lamina lucida and dermis): Significantly lower levels of collagen IV have been identified at the base of wrinkles. The mechanical stability of the dermal-epidermal junction (DEJ) may be adversely affected by this loss of collagen IV, thereby contributing to wrinkle formation.
   • lamina reticularis (of dermis origin containing fibronectin):
   • rete ridges (epidermal thickenings that extend downward between dermal papillae): reduced rete pegs/rete ridges that will adversely affect the absorption of nutrients and oxygen from capillary into the epidermal cells.

II. Structures of Dermal Origin

1. anchoring fibrils (composed largely of type VII collagen): degradation of anchoring fibrils/decrease of collagen VII, wrinkles may form as a result of a weakened bond between the dermis and epidermis.
2. dermal papillae (interdigitations of the dermis into the epidermis): flattened and widened under scanning electron microscopy
3. dermal microfibrils of the elastic system: decrease of oxytalin fibers (the most superficial elastic fibers forming the elastic system of skin ( oxytalan, elaunin, and elastic fibers)

III. Histological studies show the flattening of the dermal-epidermal junction.

Flattening of the dermal-epidermal junction appears in both photoaged and chronologically aged skin and is considered as one of the telltale signs of aging. The physiologic consequence of this flattening is the
increased susceptibility to shearing forces, the epidermis can be easily torn from the dermis.

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Age-Related Changes in Skin Epidermal-Dermal Junction