Overhuden

Overhuden is the outermost layer of the skin in vertebrates. It is a protective barrier that prevents water loss and shields the body from environmental factors, pathogens, and UV radiation. This avascular layer is composed of stratified squamous epithelium, meaning it is made of multiple layers of flattened cells. The outermost cells of the epidermis are constantly shedding and being replaced by new cells generated from the basal layer, also known as the stratum basale.

The epidermis is divided into several sublayers, or strata. From deepest to most superficial, these are the stratum basale, stratum spinosum, stratum granulosum, stratum lucidum (found only in thick skin like palms and soles), and stratum corneum. Melanocytes, pigment-producing cells, are found in the stratum basale and contribute to skin color and UV protection. Keratinocytes, the primary cells of the epidermis, produce keratin, a tough protein that provides structural integrity to the skin and nails.

The thickness of the epidermis varies across different parts of the body. It is thinnest on the eyelids and thickest on the soles of the feet and palms of the hands. This variation in thickness correlates with the level of protection and abrasion the skin is exposed to in different areas. The epidermis plays a crucial role in maintaining homeostasis and is the first line of defense for the body.