Connective Tissue

Types of Connective Tissue Proper

loose – high cell density, loose fibers

dense – low cell density, dense fibers

Specialized connective tissue

Connective Tissue Fibers

collagen

most abundant (30% of body protein)

bundles of fibrils

large family, not all fibrous

repeat: Gly-x-y (x: pro; y: hydroxypro)

fibrils formed by cell, assembled in ECM

elastic fibers: elastin, microfibrillar proteins, lysyl oxidase, proteoglycans?

reticular fibers

ground substance – proteoglycans and glycosaminoglycans

Non-collagenous proteins

Connective Tissue Cells

Resident cells

macrophage: phagocytosis, sec of proteins related to immune response (anaphylaxis and inflammation)

mast cell: release of active substances upon exposure to antigen in sensitized individual

Transient cells

Other cells

unidentified mesenchymal cells: tissue renewal; can give rise to differentiated cells; used in extensive regen

Some Examples of Connective Tissue

Tendon: connective tissue proper

Cartilage

hyaline cartilage: most common; type II collagen; articular joint surfaces; growth plates
elastic cartilage: type II and elastic fibers; has perichondrium; found in ear
fibrocartilage: great stress and weightbearing; intervertebral discs; tendon attachment

Basement membranes – interface between histologically different tissues