stratum spinosum, one of the layers of the epidermis, composed of several layers of polygonal cells. It lies on top of the stratum basale and beneath the stratum granulosum and contains tiny fibrils within its cellular cytoplasm. When the cells of the stratum spinosum are pulled apart, they present minute spines, called desmosomes, at their surfaces. Also called prickle cell layer. Compare stratum basale, stratum corneum, stratum granulosum, stratum lucidum. See also skin.
