HISTOLOGY REVIEW The Skin Dr Tim Ballard Department

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

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

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

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

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

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

Skin – eccrine sweat glands Human skin – H&E – 4 x objective sweat gland duct moving towards the surface secretory portions of sweat glands 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.

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

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