The lower epidermal cells (basal layer) produce a variety of keratin filaments and desmosomal proteins (e.g.
desmoglein and desmoplakin), which make up the ‘cytoskeleton’.
This confers strength to the epidermis and prevents it shedding off.
Higher up in the granular layer, complex lipids are secreted by the keratinocytes and these form into intercellular lipid bilayers, which act as a semipermeable skin barrier.
The upper cells (stratum corneum) lose their nuclei and become surrounded by a tough impermeable ‘envelope’
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