Hoornweefsel

Hoornweefsel, also known as keratinized epithelium or horny layer, is a protective outer layer of cells found in the epidermis of vertebrates. It is composed primarily of dead, flattened cells called corneocytes, which are filled with a tough, fibrous protein called keratin. This protein provides strength and resilience to the tissue, making it an effective barrier against physical damage, chemical irritants, and microbial invasion.

The formation of hoornweefsel is a continuous process known as keratinization or cornification. Epidermal stem cells in the basal layer divide and differentiate, moving upwards through the epidermis. As these cells mature, they undergo a series of changes, accumulating keratin and losing their organelles, eventually becoming desiccated corneocytes. These dead cells are then shed from the surface of the skin in a process called desquamation.

The thickness of hoornweefsel varies depending on its location on the body. It is generally thicker in areas that experience more friction or pressure, such as the palms of the hands and the soles of the feet. This thicker layer provides enhanced protection in these areas. Hoornweefsel plays a crucial role in maintaining the integrity of the skin and preventing water loss from the body, contributing significantly to overall homeostasis.