A Histological Atlas of the Integumentary System

INTEGUMENTARY SYSTEM melanocytes (926). Skin, monkey Keratin inside denucleated cell shells stratum corneum keratohyalin granules stratum granulosum stratum spinosum stratum basale dermis dermis stratum lucidum Skin, monkey stratum corneum . The epidermal projections are known as epidermal ridges (rete pegs), while the alternating dermal extensions are termed dermal papillae. melanocytes stratum granulosum stratum spinosum stratum basale Skin, monkey rete pegs dermal papillae. The elaborate interdigitation of these two layers occurs because INTERDIGITATION INCREASES THE TOTAL AMOUNT OF SURFACE AREA TO FACILITATE ATTACHMENT OF THE EPIDERMIS TO THE DERMIS AND TO INCREASE SURFACE AREA FOR DIFFUSION OF NUTRIENTS AND GASES TO THE EPIDERMIS FROM THE DERMIS finger pad Epidermal – dermal interface creates unique finger prints stratum lucidum Rete pegs dermal papillae. Finger print Meissner’s corpuscle Light touch receptor 20x Skin, monkey sweat glands rete peg dermis rete peg Skeletal muscle Pacinian corpuscle PRESSURE RECEPTOR Skin, monkey Sweat glands White fat CCT Myoepithelial cell Sweat duct Skin from a digital pad, dog stratum granulosum stratum lucidum stratum corneum Myoepithelial cells compound hair follicles . Skin, horse sweat glands hair follicles sebaceous glands arrector pili muscles Skin, horse Melanocytes (clear cells on basal layer nuclei of myoepithelial cells sweat glands Skin, horse Skeletal muscle Sebaceous glands nerve arrector pili muscle Smooth muscle muscular artery Demo slide #215a. Skin of metacarpal pad, cat Pacinian corpuscle UNILOCULAR ADIPOSE TISSUE (WHITE FAT) COLLAGENOUS CONNECTIVE TISSUE (CCT) NERVE ENDOTHELIUM (SIMPLE SQUAMOUS EPITHELIUM) [in a BLOOD vessel] SMOOTH MUSCLE Skin, rat. sinus (tactile) hair follicles SINUS HAIRS ARE MOST NUMEROUS ON THE HEAD / FACE REGION ; THE FUNCTION OF SINUS HAIRS IS “TOUCH” RECEPTION OR ORIENTATION OF THE HEAD / FACE (OR TO A LESSER EXTENT YOU COULD SAY THE BODY) IN THE ENVIRONMENT Skin, rat. Skeletal muscle Mast cells skin and sinus hairs, rabbit. sinus (tactile) hair follicle Anal sac, dog anocutaneous junction cross section of one sac and is lined by keratinized stratified squamous epithelium Anal sac SKELETAL MUSCLE apocrine sweat glands, the glands of the anal sac WHITE Anal sac, dog apocrine sweat glands SKELETAL MUSCLE ENDOTHELIUM nerve CCT White WHITE FAT fat Anal region, dog. rectoanal junction non-keratinized epithelium, the goblet cells among disrupted simple columnar epithelium Anal region, dog. rectoanal junction and regional skin Apocrine sweat glands non-keratinized epithelium, keratinized epithelium, gut gut Circumanal gland Anal region, dog. circumanal glands are considered modified sebaceous glands non-keratinized epithelium, keratinized epithelium, Anal region, dog . circumanal glands NONKERATINIZED STRATIFIED SQUAMOUS [EPITHELIUM KERATINIZED STRATIFIED SQUAMOUS [EPITHELIUM] SIMPLE COLUMNAR [EPITHELIUM] [= RECTUM ; NOTE GOBLET CELLS ARE PRESENT] Anal region, dog. SMOOTH MUSCLE [= INTERNAL ANAL SPHINCTER] SKELETAL MUSCLE [= EXTERNAL ANAL SPHINCTER] Sheep lip tactile hair follicle Skin of lip, sheep. NONKERATINIZED STRATIFIED SQUAMOUS [EPITHELIUM] KERATINIZED STRATIFIED SQUAMOUS [EPITHELIUM] oral cavity skin skin adnexa (i.e. hair/hair follicles, sebaceous & sweat glands, arrector pili muscles Skin of lip, sheep. COLLAGENOUS CONNECTIVE TISSUE (CCT) Mixed glands SKELETAL MUSCLE UNILOCULAR ADIPOSE TISSUE (WHITE FAT) Hoof, donkey. adnexa perioplic region with predominant rete pegs dermal papilla keratinized stratified squamous epithelium rete pegs (epidermal ridges) and dermal papilla Epidermal – dermal interface Tubular horn rete pegs dermis dermis dermal papilla dermis Finger skin finger skin equine hoof dermis Hoof, donkey. coronary region epidermis dermis coronary region = the junction of the epidermis with the dermis. perioplic region STRATUM EXTERNUM stratum corneum that was produced in the perioplic region is called the STRATUM EXTERNUM Primary & secondary epidermal laminae horn tubules non-tubular or intertubular horn Hoof, donkey. coronary region dermis stratum basale (note the melanocytes and melanin pigment) and stratum spinosum Equine hoof (H&E – BOX 28 & trichrome – BOX 29 horn tubules non-tubular or intertubular horn Primary & secondary epidermal laminae Equine hoof (H&E – BOX 28 & trichrome – BOX 29 CCT of the corium will stain blue and the epidermal structures will stain red Primary & secondary epidermal laminae horn tubules non-tubular or intertubular horn Equine hoof (H&E – BOX 28) is unique with its secondary epidermal laminae SECONDARY LAMINAE ALLOW OR PROVIDE INCREASED SURFACE AREA FOR ATTACHMENT OF THE HOOF WALL TO BONE TO HELP SUSPEND THE WEIGHT OF THE HORSE BETWEEN THE HOOF WALL AND THE DISTAL PHALANX Hoof, fetal goat ruminants do NOT possess secondary laminae (either epidermal or dermal). All cloven hoofed animals (which includes pigs) will have hooves that both grossly and microscopically resemble the ruminant hoof. primary epidermal laminae CORIUM Bone = SPONGY (TRABECULAR OR CANCELLOUS) digital cushion Hoof, fetal goat stratum medium stratum externum primary epidermal laminae CCT Epithelium stratum medium stratum externum stratum externum is composed of horn tubules (tubular horn) and intertubular horn, just like the stratum medium Fetal goat hoof. CCT that is forming tendons Hyaline cartilage that forms articular cartilage Primary dermal and epidermal laminae Hair follicles of Integument adnexa nonarticular hyaline cartilage Collagenous connective tissue (CCT), growth plate with the four zones of cartilage Developing bones and synovial joint, kitten. primary center of ossification Zone of reserve (resting) cartilage—this zone appears as an area of typical hyaline cartilage. Zone of proliferative chondrocytes—characterized by chondrocytes that are arranged in rows (like stacks of coins). Zone of mature (hypertrophied) chondrocytes—in this zone, both the chondrocytes and lacunae have enlarged at the expense of the matrix, reducing it (the matrix) to thin strands. Zone of calcified chondrocytes/cartilage matrix— Zone of erosion and ossification Fetal goat hoof. Primary dermal and epidermal laminae CCT that is forming tendons Spongy or (trabecular/cancellous) bone and Periostium Hyaline cartilage Fetal goat hoof. Arrector pili muscles Hyaline cartilage Integument, including adnexa: hoof bone Integument, including adnexa: Hair Hair follicles Sebaceous glands Cat claw. corium epidermis (including the strata basale, spinosum, and corneum of the wall) claw Cat claw. epidermis (including the corneum of the wall, Spinosum, and strata basale) Corium Cat claw Central (dorsal) ridge Claw fold Region of the coronary border Claw plate corium sole Tip of claw