Epidermisoluja

Epidermisoluja, or epidermal cells, are the cells that form the epidermis, the outermost layer of the skin and other epithelial surfaces. They originate from the embryonic ectoderm and organize into a stratified epithelium that protects underlying tissues.

The epidermis is dominated by keratinocytes, which arise in the basal layer (stratum basale) and migrate outward as they differentiate and keratinize, eventually forming the protective stratum corneum. Other epidermal cell types include melanocytes, which produce pigment; Langerhans cells, which are dendritic immune cells; and Merkel cells, which function as tactile receptors.

Epidermal structure is typically described in layers: stratum basale, stratum spinosum, stratum granulosum, stratum lucidum (present only in thick skin), and stratum corneum. Keratinocytes form intercellular junctions such as desmosomes and tight junctions, and granule-containing cells release lipids that contribute to the barrier properties of the epidermis.

The primary functions of epidermal cells are to form a barrier against mechanical injury, pathogens, and water loss, and to participate in immune defense. Melanocytes influence skin color through pigment transfer to keratinocytes, while Merkel cells contribute to light touch sensation.

Renewal of epidermal cells is continuous. Basal keratinocytes divide to replace cells shed from the surface, with turnover times on the order of weeks. Thickness and cellular composition vary by body site, with thick skin on the palms and soles and thinner skin elsewhere.

Dysfunctions of epidermal cells are involved in various conditions, including psoriasis and dermatitis, as well as skin cancers such as basal cell carcinoma, squamous cell carcinoma, and melanoma.