Connective Tissue: Adipose, Areolar, Reticular, and Dense Regular Collagenous

Adipose Tissue

  • Structure: Little extracellular matrix surrounding cells; the adipocytes are so full of lipid that the cytoplasm is pushed to the periphery of the cell.
  • Function: Packing material, thermal insulation, energy storage, and protection of organs against injury from being bumped or jarred.
  • Location: Predominantly in subcutaneous areas, in mesenteries, in renal pelvis, around kidneys, attached to the surface of the colon, in mammary glands, in loose connective tissue that penetrates spaces and crevices.
  • Magnification notes: LM 100x.

Areolar Connective Tissue

  • Structure: Cells (e.g., fibroblasts, macrophages, and lymphocytes) within a fine network of mostly collagen fibers; often merges with denser connective tissue.
  • Function: Loose packing, support, and nourishment for the structures with which it is associated.
  • Location: Widely distributed throughout the body; substance on which epithelial basement membranes rest; packing between glands, muscles, and nerves; attaches the skin to underlying tissues.
  • Diagram cues: Nucleus; Elastic fiber; Collagen fiber.
  • Magnification notes: LM 400x.

Reticular Tissue

  • Structure: Fine network of reticular fibers irregularly arranged.
  • Function: Provides a superstructure for lymphatic and hemopoietic tissues.
  • Location: Within the lymph nodes, spleen, bone marrow.
  • Magnification notes: LM 280x.

Dense Regular Collagenous Connective Tissue

  • Structure: Has abundant collagen fibers that resist stretching.
  • Subtypes and main roles:
    • Tendons: connect muscles to bones.
    • Ligaments: connect bones to bones.
  • Additional features: Collagen often less compact, usually flattened, form sheets or bands.
  • Fiber orientation: Fibers are not necessarily parallel.
  • Magnification notes: LM 165x.