American Academy of Professional Coders (AAPC) Practice Exam 2026 - Free AAPC Practice Questions and Exam Prep Guide

The stratum basale, also known as the basal layer, is the deepest layer of the epidermis and is primarily composed of basal cells. These cells are actively dividing keratinocytes that serve as the foundation for the formation of new skin cells. As these basal cells undergo mitosis, they push older cells upwards through the layers of the epidermis, eventually leading to the formation of the outermost protective layer, which consists of dead keratinized cells.

Basal cells are characterized by their cuboidal or columnar shape and possess the ability to differentiate into various types of skin cells. They are essential for maintaining the integrity and health of the epidermis. The presence of these vital cells in the stratum basale is crucial for skin regeneration and repair processes.

The other choices pertain to cell types that do not typically reside in the stratum basale. Dead keratinized cells are found in the outer layers of the skin, while squamous cells and columnar cells are associated with different types of tissues or layers within the body and are not characteristic of the stratum basale.