What is the stratum spinosum?

The stratum spinosum, also known as the spinous layer or prickle cell layer, is a layer of cells in the epidermis, which is the outermost layer of the skin. It is located just above the stratum basale (basal layer) and below the stratum granulosum (granular layer) in the epidermal layers.

The cells in the stratum spinosum are called spinous or prickle cells because they appear spiky or prickly under a microscope. These cells are typically polygonal in shape and are interconnected by structures called desmosomes, which are specialized cell junctions that provide strength and stability to the skin.

The primary functions of the stratum spinosum include:

Providing mechanical support and strength to the skin.
Assisting in the process of keratinization, which is the transformation of keratinocytes (skin cells) into tough, waterproof, and protective keratin-filled cells as they move upward through the epidermal layers.
Participating in the immune response of the skin by housing Langerhans cells, which are specialized immune cells that help protect the body from pathogens and foreign substances.
As cells move upward from the stratum basale through the stratum spinosum and eventually into the stratum granulosum, they undergo changes in morphology and function to fulfill their role in maintaining the integrity and barrier function of the skin.