Skin pigmentation


Skin explanatory video

Pigmentation of the skin carried out through the agency of the cells known as melanocytes.  The dendritic melanocytes form the second cellular components of the epidermis.  The remaining epithelia cells are of the squamous type.  Other types of cells called the epidermal melanoblasts also exist. They are found in the epidermis.  There are also dermal melanoblasts found in the dermis.  All these cells contain melanin which is the skin dark pigment.  The DOPA reaction is positive  in the cells that produce melanin only. It is negative in those cells that do not produce or contain melanin and also in those cells that contain melanin but do produce it.  The basis of this DOPA histochemical reaction is as follows.  When DOPA is introduced to tissue, the cells that contain DDPA oxidase convert DOPA to melanin.  The melanin pigment is black, the cells that contain DOPA oxidase convert DOPA to melanin.  The melanin pigment is black.

            These are four different types of pigments which color the skin in man

1.  Melanin

2.  Carotene

3.  Oxyhemoglobin

4.  Reduced hemoglobin

             Skin pigmentation describes three human races in relation to their preponderance

1.  Leucoderms white skinned

2.  Melanoderms black skinned

3.  Xanthoderms yellow skinned

 

d)    


Blue eyes in black and white due to lack of pigmentation of the iris

 

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Creator: Oluwole Ogunranti