Anatomy of Connective Tissue

Introduction

• Connective Tissue: Basic tissue type in the body that supports, connects, and binds other tissues.
• Categories:
  • Connective Tissue Proper: Subdivided into loose and dense connective tissues.
  • Specialized Connective Tissue: Includes adipose, cartilage, bone, blood, and reticular tissues.
• Features: Structural and functional commonality across diverse types.

Structure and Function

• Functions: Support organs, transport nutrients/wastes, defense against pathogens, fat storage, tissue repair.
• Components: Primarily extracellular matrix and few cells.
• Fluid Connective Tissues: Blood and lymph lack fibers.
• Subcategories:
  • Connective Tissue Proper:
    • Loose Connective Tissue: Areolar tissue; holds organs and tissues in place.
    • Dense Connective Tissue: High fiber density; regular (tendons/ligaments) or irregular (pericardium), elastic (arteries).
  • Extracellular Matrix:
    • Collagen, Reticular, and Elastic Fibers: Different fiber types with distinct properties.

Specialized Connective Tissue

• Types: Adipose, cartilage, bone, blood, lymphatic tissues.
• Functions:
  • Adipose Tissue: Energy storage, insulation, protection, hormone secretion.
  • Cartilage: Flexible support, reduces bone friction, shock absorber.
  • Bone: Rigid support, organ protection, movement, mineral storage, hematopoiesis.
  • Blood/Lymph: Fluid connective tissue for transport and immune response.

Embryology

• Embryonic Connective Tissue: Includes mucoid (Wharton's jelly) and mesenchyme.
• Development: Mesenchyme from mesoderm, differentiates into various tissues.
• Tendon Development: Involves scleraxis, fibroblast factors, TGF-beta.

Blood Supply and Lymphatics

• Vascularization: Most connective tissues are well-vascularized except cartilage.
• Cartilage: Avascular, relies on diffusion for nutrient supply.

Nerves

• Peripheral Nerve Structure: Three connective tissue layers (epineurium, perineurium, endoneurium).

Muscles

• Structure:
  • Muscle cells form fibers, fibers form fascicles, and fascicles form muscles.
  • Connective tissue (endomysium, perimysium, epimysium) supports muscle structure.
  • Collagen and elastin are key components of tendon connective tissue.

Clinical Significance

• Pathologies: Tendon tears, fractures, compartment syndromes, connective tissue injuries.
• Autoimmune Diseases:
  • Systemic Lupus Erythematosus: Inflammation of organs, common in females/non-whites.
  • Scleroderma: Fibrosis due to excess collagen, more common in males.
  • Myositis: Muscle inflammation.
  • Rheumatoid Arthritis: Chronic tissue inflammation, disability.
  • Sjogren Syndrome: Dry eyes/mouth, organ damage.
• Undifferentiated Connective Tissue Disease: Symptoms suggestive of connective tissue disease without full criteria.
• Overlap Syndromes: Multiple autoimmune diseases, e.g., Mixed Connective Tissue Disease.
• Gene Defect-Related Conditions:
  • Ehlers-Danlos Syndrome: Hyperflexibility and elastic skin.
  • Marfan Syndrome: Tall, thin body structure.
  • Epidermolysis Bullosa: Fragile skin.
  • Osteogenesis Imperfecta: Brittle bones.