Ch. 4: Tissue: The Living Fabric HESC310 4/26/2017 Ch. 4: Tissue: The Living Fabric Microscopy Epithelial Tissue Connective Tissue Nervous Tissue Muscle Tissue Covering and Lining Membranes Wound repair; development Ch. 4

Microscopy Microscopic Anatomy Fix (Preserve) Section (Slice) Stain (Add Contrast) Light Microscopy Add color Different stains for different tissues H&E the default Different aspects of different tissues Electron Microscopy Add heavy metal to deflect electron beam Artifacts of fixation, sectioning, staining

Skeletal muscle, H&E stain www.anatomy.uiowa.edu/genhisto/GHWIN/unit1/image/i-08.jpg

Light microscopy: organ of Corti, ear Keele University, UK, www.keele.ac.uk/depts/bi/emunit/galleries/gallery1/index.htm

Scanning electron microscopy: organ of Corti, ear Keele University, UK, www.keele.ac.uk/depts/co/em96/em96.htm

Outer hair cells, ear Scanning and transmission electron micrographs Keele University, UK, www.keele.ac.uk/depts/co/em96/em96.htm

Epithelial Tissue Special Characteristics Polarity, sidedness: apical (microvilli), basal Specialized contacts on the sides: tight junctions, desmosomes Supported by connective tissue: basal lamina (noncellular) and reticular connective tissue below Avascular, innervated High regeneration rate Classification Glandular

Epithelial Tissue Special Characteristics Classification Two-part names Part 1: cell layers Simple (1), stratified (>1) Part 2: shape (of apical layer in stratified) Squamous, cuboidal, columnar Glandular

Figure 4.1

Figure 4.2a

Figure 4.2b

Figure 4.2c

Figure 4.2d

Figure 4.2e

Figure 4.2f

Epithelial Tissue Special Characteristics Classification Glandular Endocrine glands Make & release hormones into blood; ductless; most are small organs; ch. 16 Exocrine glands Make & secrete product to “outside” Unicellualr: goblet cell make mucin, forms mucus; resp & GI tracts Multicellular: duct & secretory unit (acinus); sweat, various in GI tract, mammary, salivary

Goblet cell Unicellular exocrine gland Figure 4.3

Types of multicellular exocrine glands HESC310 Types of multicellular exocrine glands Classified by structure 4/26/2017 Figure 4.4 Ch. 4

Connective Tissue Common Characteristics Origin: embryonic mesenchyme Large amount of extracellular matrix Structural Elements Ground substance – between the cells Fibers Collagen Elastic Reticular Cells See Fig 4.6. -blasts vs. -cytes Types

HESC310 4/26/2017 Figure 4.6 Ch. 4

Connective Tissue Types Connective Tissue Proper Loose Areolar: support, hold fluid, defense v. infection Adipose: cushion, store energy, insulate; often subQ Reticular: like areolar but only retic fibers; many lymphocytes; lymph nodes, spleen, bone marrow Dense (Fibrous: fibers are main component) Regular: unidirectional collagen fibers; ligaments, tendons Irregular: multidirectional collagen fibers; makes sheets; dermis, joint capsules, etc. Elastic: elastic (large) arteries Cartilage Bone Blood

Areolar connective tissue as general connective tissue example Extracellular matrix Cell types Ground substance Macrophage • Collagen fiber • Elastic fiber • Reticular fiber Fibroblast Lymphocyte Fat cell Capillary Mast cell Neutrophil Figure 4.7

Figure 4.8a

Figure 4.8b

Figure 4.8c

Figure 4.8d

Figure 4.8e

(f) Connective tissue proper: dense connective tissue, elastic Description: Dense regular connective tissue containing a high proportion of elastic fibers. Function: Allows recoil of tissue following stretching; maintains pulsatile flow of blood through arteries; aids passive recoil of lungs following inspiration. Location: Walls of large arteries; within certain ligaments associated with the vertebral column; within the walls of the bronchial tubes. Elastic fibers Aorta Elastic connective tissue in the wall of the aorta (250x) Heart Figure 4.8f

Connective Tissue Common Characteristics Structural Elements Types Connective Tissue Proper Cartilage Hyaline c. Elastic c. Fibrocartilage Bone Blood

Collagen Most abundant protein in the body Type I (most common): In bone, scar tissue, tendons, ligaments. Type II: Hyaline cartilage. Type III: Found in extracellular matrix of early granulation (wound healing) tissue; replaced by type I collagen in mature scar tissue. Type IV: Lens of eye; basal lamina beneath epithelium (esp. in skin, beneath epidermis); capillaries, including glomeruli. Type V: Interstitial tissue (loose connective tissue); placenta. List goes up to XXVIII=28…

Collagen Structure Has 3 subunits (strands) which wrap around each other with a right-handed (RH) twist – i.e. a triple helix. Each subunit (strand) is a LH helix (not an a-helix which is RH). Combination of RH and LH helices makes collagen hard to stretch. How to tell the handedness of a helix: fingers show sense of rotation when travelling in direction that thumb points. Julian Voss-Andreae "Unraveling Collagen: a metaphor for aging and growth” http://en.wikipedia.org/wiki/Image:Collagentriplehelix.png

Figure 4.8g

Figure 4.8h

Figure 4.8i

Connective Tissue Common Characteristics Structural Elements Types Connective Tissue Proper Cartilage Bone Blood

Figure 4.8j

Connective Tissue Common Characteristics Structural Elements Types Connective Tissue Proper Cartilage Bone Blood Develops from mesenchyme Has a noncellular matrix - plasma

Figure 4.8k

Nervous Tissue Neurons Excitable (electro-chemically) Brain, spinal cord, nerves, some organs Cell body = soma Dendrites receive input Axon carries output Neuroglia = glial cells Support, insulate (electrically), protect Not excitable

Figure 4.9

Muscle Tissue Types of Muscle By Looks: striated vs smooth Striated Skeletal Cardiac Smooth By control: voluntary vs involuntary Voluntary: skeletal Involuntary: cardiac, smooth

Figure 4.10a

Figure 4.10b

Figure 4.10c

Covering and Lining Membranes Cutaneous membrane (Skin) “largest organ”; epidermis over dermis; dry; ch. 5 Mucous membranes (mucosae) Line body cavities that connect to outside; wet Simple columnar or stratified squamous epithelium over lamina propria (loose areolar conn. tiss.) Often adapted for absorption & secretion Some but not all secrete mucus Serous membranes (serosae) In ventral body cavities: thorax, abdominopelvic Have inner (visceral) & outer (parietal) layers

Figure 4.11

Figure 4.11

Minor skin wound repair: regeneration and fibrosis Scab Blood clot in incised wound Regenerating epithelium Regenerated epithelium Epidermis Area of granulation tissue ingrowth Vein Fibroblast Macrophage Migrating white blood cell Inflammatory chemicals Artery Fibrosed area Fig. 4.12 1 Inflammation sets the stage: • Severed blood vessels bleed and inflammatory chemicals are released. • Local blood vessels become more permeable, allowing white blood cells, fluid, clotting proteins and other plasma proteins to seep into the injured area. • Clotting occurs; surface dries and forms a scab. 2 Organization restores the blood supply: • The clot is replaced by granulation tissue, which restores the vascular supply. • Fibroblasts produce collagen fibers that bridge the gap. • Macrophages phagocytize cell debris. • Surface epithelial cells multiply and migrate over the granulation tissue. 3 Regeneration and fibrosis effect permanent repair: • The fibrosed area matures and contracts; the epithelium thickens. • A fully regenerated epithelium with an underlying area of scar tissue results.

Where it comes from: embryonic germ layers ectoderm, mesoderm, endoderm (outer, middle, inner) 16-day-old embryo (dorsal surface view, cephalic end up, length 1 mm) Muscle and connective tissue (mostly from mesoderm) Ectoderm Mesoderm Nervous tissue (from ectoderm) Endoderm Epithelium Figure 4.13 See also Medical Embryology, 4th ed, Langman, 1981.