Final answer:
The needle would pierce the epidermal layers of the forearm in the following order: stratum basale, stratum spinosum, stratum granulosum, and finally, the most superficial layer, the stratum corneum.
Step-by-step explanation:
The needle would pierce the epidermal layers of the forearm in the following order: stratum basale, stratum spinosum, stratum granulosum, and finally, the most superficial layer, the stratum corneum.
The stratum basale is the innermost layer of the epidermis, composed of epidermal stem cells.
The stratum spinosum is the thickest layer and contains Langerhans cells and spiny keratinocytes.
The stratum granulosum is where the keratinocytes start to fill with keratin and die.
The stratum corneum is the outermost layer, consisting of flat, dead, tightly packed keratinocytes that form a tough, waterproof barrier for the rest of the epidermis.