Figure 1. This image was adapted from PulpBits, 2013 it Illustrates the skin structure from the epidermis to the
dermis and the hypodermis with the various structures present in each layer.
Structure of the skin
One of the primary cell types present in the epidermis is the keratinocyte. These cells can be found from the
basal to the granular layer; where they transform into corneocytes of the SC (Wickett and Visscher, 2006).
Corneocytes exist in a lipid bilayer structure, these bilayers are created from free fatty acids, cholesterol,
and ceramides. The bilayers contribute to the barrier function of the skin, hence if the SC lipid bilayers are
diminished or disturbed; this can lead to a reduced function in the skin’s barrier as well as leading to diseases
such as atopic dermatitis and psoriasis which both have unpleasant symptoms (Sahle et al., 2015).
Studies of skin physiology in different ethnic groups
Studies have been carried out to determine whether the SC of different ethnic groups varies, however, studies
have proven that the thickness of the SC layer is equal within different ethnic groups (Rawling, 2006). On
the other hand, in terms of the amount of the SC Weigand et al., 1974 proved that black skin contains more
cell layers of the corneocytes in the SC compared to Caucasian skin from their tape stripping experiment.
Tape stripping is a method used to collect a thin layer of the SC, this skin layer can then be used to assess
the quality of different drug and cosmetic formulations (Lademann et al., 2009). The results from this study
indicated that more tape strips were needed to disrupt the epidermal barrier with black skin which accounted
for the removal of the SC layer (Weigand et al., 1974). As the thickness of the SC was shown to be the same
within all ethnicities, it was then suggested that the cell layers in black ethnic skin are tightly packed together.
Due to these findings, it was further suggested that there is greater intercellular cohesion in black individuals,
which explained the reasons as to why black skin required more tapes stripes (Rawling, 2006).
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