Skin covers the external surface of our body and consists of the epidermis and the dermis. Together with epidermal derivatives (e.g. hair, sweat glands, sebaceous glands, and nails) it constitutes our integumentary system. The mammary gland is also a derivative of the epidermis.

Learning outcomes

You should be able to recognize the following structural components of thick and thin skin (where applicable) and know their functional significances:

• Epidermis, stratum basale (germinativum), stratum spinosum, stratum granulosum, keratohyalin granules, stratum lucidum, stratum corneum.
• Keratinocyte, melanocyte, melanin granule, Langerhans’ (antigen-presenting) cell and Merkel cell.
• Epidermal peg.
• Dermis – dermal papilla, papillary layer, reticular layer.
• Hypodermis.
• Meissner’s corpuscle and Pacinian corpuscle.
• Eccrine sweat gland – duct portion, secretory portion, myoepithelial cell.
• Apocrine sweat gland.
• Sebaceous gland – basal cell, secretory acinus.
• Hair – hair follicle, hair root (bulb), inner root sheath, outer root sheath, arrector pili muscle.
• Nail – nail matrix, nail root.