What occurs in the stratum spinosum layer of the skin?

The stratum spinosum, often referred to as the "spiny layer," is a crucial part of the epidermis, situated above the stratum basale and below the stratum granulosum. One of the primary functions of the stratum spinosum is to provide strength and flexibility to the skin.

In this layer, keratinocytes, which are the predominant cell type, begin to flatten and lose their round shape as they move upwards from the deeper layers. This change is a part of the process of keratinization, where cells begin to compact and ultimately die as they are further away from the nourishing effects of the dermal blood supply. The lack of blood vessels in the epidermis means that cells start receiving less oxygen and nutrients as they ascend through the layers, leading to the cessation of metabolic activity and eventual cell death.

As cells in the stratum spinosum die, they become more tightly packed and play a significant role in forming a robust barrier for the skin. This layer also contains desmosomes, which provide mechanical strength and keep the cells connected, contributing to the overall integrity of the epidermis.

The other options, while they may pertain to other layers or processes in the skin, do not