In Experiment 5, how did the shape of the epidermal cells in the outer skin surface slide compare to the shape of the epidermal cells in the skin cross section slide?

A. The cells in the outer skin surface were perfectly spherical, whereas the cells in the cross section were irregular.

B. The cells in the outer skin surface appeared flat, whereas the cells in the cross section were not flat.

C. The cells appeared identical in both slides.

D. The cells in the cross section looked elongated, whereas the cells in the outer skin surface appeared cuboidal.

The correct answer is B. The cells in the outer skin surface appeared flat, whereas the cells in the cross section were not flat.

Explanation:

The epidermis is made up of five cell layers, which have different functions: Stratum basale, stratum spinosum, stratum granulosum, stratum lucidum, and stratum corneum.

Stratum basale is the innermost germinative, single, basal layer of the epidermis composed of basal cuboidal-shaped cells. These cells are the precursor of keratinocytes, this is why this layer is also called germinativum. In this basal layer, there are also Merkel cells as well as melanocytes. Stratum spinosum refers to the keratinocytes which produce keratin. Stratum granulosum, this is the layer where keratinization begins. Cells produce hard granules that change to keratin and lipids as they ascend. Stratum lucidum is conformed of densely compressed cells, which begins to flatten and appear indistinguishable between each other. Stratum corneum is the most external layer, composed of dead, flattened cells which are released regularly in a process known as desquamation.