BIO 240 HISTOLOGY REVIEWBIO 240 HISTOLOGY REVIEWThe SkinThe Skin

Dr. Tim BallardDr. Tim Ballard

Department of Biology and Marine BiologyDepartment of Biology and Marine Biology

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 featuresSkin – general features

epidermis

dermis

Human skin – H&E – 40x objective

This is a section of thin skin, so the stratum lucidum is not present.

Skin (thin) - epidermisSkin (thin) - epidermis

stratum basale

stratum spinosum

stratum granulosum

stratum corneum

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) - epidermisSkin (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

Pig skin – H&E – 10x objective

The reticular dermis has a looser arrangement of fibers than does the papillary dermis.

Skin - dermisSkin - dermis

epidermis

dermis

papillary dermis

reticular dermis

dermal papilla

Human skin – H&E – 4x objective

In this section the coiled tubular portions of eccrine sweat glands are seen in the reticular dermis.

Skin – dermisSkin – dermis

epidermis

dermis

papillary dermis

reticular dermis

dermal papilla

sweat glands

Human skin – H&E – 4x objective

Skin – eccrine sweat glandsSkin – 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.

Lip – H&E – 4x objective

Sebaceous glands are oil (sebum) glands of mammalian skin, always associated with hair follicles.

Skin – sebaceous glandsSkin – sebaceous glands

sebaceous glands

epidermis

hair follicles

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 glandsSkin – sebaceous glands

sebaceous gland

hair follicles