1. HISTOLOGY REVIEW The Skin Dr. Tim Ballard Department of Biology and Marine Biology

2. Human skin – H&E – 10x objective The arrowheads indicate the position of the basement membrane, separating the keratinized stratified squamous epithelium from the dermis below. Skin – general features epidermis dermis

3. Human skin – H&E – 40x objective This is a section of thin skin, so the stratum lucidum is not present. Skin (thin) - epidermis stratum basale stratum spinosum stratum granulosum stratum corneum

4. Human skin – H&E – 40x objective To identify a melanocyte in the stratum basale, look for granules of brown- black pigments in and around cells in this layer. Skin (thin) - epidermis stratum basale – mitotic cells giving rise to the keratinizing system with melanocytes scattered about stratum spinosum – cells receiving melanin from melanocytes and moving towards the surface stratum granulosum – several layers of living cells accumulating granules of keratohyaline stratum corneum – multiple layers of dead squamous cells filled with keratin

5. Pig skin – H&E – 10x objective The reticular dermis has a looser arrangement of fibers than does the papillary dermis. Skin - dermis epidermis dermis papillary dermis reticular dermis dermal papilla

6. Human skin – H&E – 4x objective In this section the coiled tubular portions of eccrine sweat glands are seen in the reticular dermis. Skin – dermis epidermis dermis papillary dermis reticular dermis dermal papilla sweat glands

7. Human skin – H&E – 4x objective Skin – eccrine sweat glands secretory portions of sweat glands sweat gland duct moving towards the surface Eccrine sweat glands are simple coiled tubular glands. The secretory portion lies deep in the dermis. The duct is a straight tube that opens on the surface.

8. Lip – H&E – 4x objective Sebaceous glands are oil (sebum) glands of mammalian skin, always associated with hair follicles. Skin – sebaceous glands sebaceous glands epidermis hair follicles

9. Lip – H&E – 20x objective The gland is formed as a sac of cells that opens into a hair follicle. The secretion is called sebum. Skin – sebaceous glands sebaceous gland hair follicles end