Where are epithelial cells primarily located?

Epithelial cells are primarily found in various locations throughout the body, serving crucial functions such as protection, secretion, absorption, and sensation. In this context, the basal level of the dermis, which is part of the integumentary system, houses epithelial cells in the form of the epidermis. The epidermis is the outermost layer of skin composed of stratified squamous epithelial cells that protect against environmental damage, pathogens, and fluid loss.

The other choices do not represent locations where epithelial cells are primarily located. Bone marrow is primarily associated with hematopoietic (blood-forming) cells, not epithelial cells. Muscle tissues consist of specialized muscle cells, not epithelial cells. The sub-ventricular zone is a region in the brain associated with neural stem cells, which are distinctly different from epithelial cells. Thus, the presence of epithelial cells at the basal level of the dermis underscores their importance in skin structure and function.