Connective Tissue Quiz

Defining Connective Tissue

• Connective tissue is a group of tissues sharing common developmental and structural properties.
• Supporting connective tissue provides structure, mechanical strength, space-filling, physical, and metabolic support for specialized cells.
• Connective tissue arises from mesenchyme cells (embryonic tissue).
• Embryonic connective tissue exists in the umbilical cord and developing tooth pulp.

Mesenchyme and Other Connective Tissues

• Mesenchyme cells contribute to various connective tissues like cartilage, bone, and blood.
• Connective tissue comprises cells and extracellular material (matrix).
• The matrix contains connective tissue fluid (ground substance), and various protein fibers (collagen, reticular, elastic).

Connective Tissue Functions

• Connective tissue binds, anchors, and supports cells, tissues, and organs.
• Ground substance provides a gel-like environment for nutrient, oxygen, and waste exchange.
• Connective matrix contains cells for protection and defense.

Structural properties of Connective Tissue

• Tensile strength: resists pulling, stretching, and tearing.
• Elasticity: allows return to original shape after distortion.
• Volume arises from glycoproteins and complex carbohydrates forming a gel-like ground substance.

Classification of Connective Tissue

Loose Connective Tissue

• Widespread, irregular arrangement of tissue fibers.
• Abundant ground substance.
• Includes collagen fibers, fibroblasts, adipose cells, mast cells, plasma cells, macrophages.

Dense Connective Tissue

• Contains thicker, densely packed collagen fibers.
• Fewer cell types and less ground substance.
• Collagen fibers exhibit random, irregular orientation.
• Found in the dermis of skin and capsules of organs requiring strong binding and support.
• Dense regular connective tissue has parallel collagen fibers (e.g., tendons, ligaments).

Cells of Connective Tissue

• Fibroblasts (produce fibers).
• Fibrocytes (maintain fibers).
• Adipocytes (fat cells – white, brown).
• Macrophages (phagocytic).
• Mast cells (release mediators).
• Plasma cells (produce antibodies).
• Leukocytes (immune cells).

Types of Collagen Fibers

• Thick, fibrous proteins not branching.
• Type I: dermis, tendons, ligaments, fasciae, fibrocartilage, organ capsules, bones.
• Type II: hyaline cartilage, elastic cartilage, vitreous body.
• Type III: delicate meshwork in lymph nodes, spleen, bone marrow.
• Type IV: meshwork in basal lamina (basement membrane) where cells attach.

Reticular Fibers

• Composed primarily of type III collagen.
• Thin, forming a delicate network.
• Support frameworks in liver, lymph nodes, spleen, hemopoietic organs.
• Support capillaries, nerves, and muscle cells in various locations.

Elastic Fibers

• Thin, branching fibers.
• Capable of stretching and returning to their original state.
• Composed of microfibrils and elastin protein.
• Found in abundance in lungs, bladder walls, skin.
• Allow for stretching and recoil of blood vessels (e.g., aorta, pulmonary trunk).

Types of Cells (Images)

• Detailed images of various connective tissue cells.

Connective Tissue, Capillary, and Mast Cell in Mesentery of Small Intestine

• Describes micrograph of small intestine mesentery.
• Shows mast cells, capillaries (with RBCs), venules, and adipose tissue.
• Also presents collagen fibers closely associated with blood vessels and capillaries.

Loose Connective Tissue (Detailed)

• Collagen fibers are prominent, running in different directions, forming a loose meshwork.
• Fibroblasts are numerous.
• Blood cells (neutrophils, eosinophils, small lymphocytes) are seen.
• Adipose cells with thin cytoplasm and displaced nuclei.

Dense Irregular and Loose Irregular Connective Tissue (Elastin Stain)

• Elastic fibers are stained deep blue.
• Collagen fibers are stained red using a counterstain.
• Fibroblast nuclei are stained blue.
• Blood vessels are present.

Loose Irregular and Dense Irregular Connective Tissue (Comparison)

• Collagen fibers are large, in bundles, and run in multiple planes within both tissues.
• Dense tissue often compresses fibroblasts into spaces between fibers, while loose packing allows for more visible cells (including capillaries, venules, eosinophils, lymphocytes, plasma cells, and adipose cells).

Dense Regular Connective Tissue: Tendon (Longitudinal Section)

• Collagen fibers are arranged parallel, compact bundles.
• Thin interstitial connective tissue containing fibroblasts.
• Blood vessels supplying the connective tissue cells exist in the interfascicular space.

Loose Collagenous Connective Tissue of the Dental Pulp

• Loose tissue, appearance similar to mesenchyme.
• Large intercellular spaces (filled with hydrated glycosaminoglycans).

Dense Regular Connective Tissue of a Tendon

• Fibrocytes have spindle-like shapes and nuclei with basophilic staining.
• Collagen fibers are parallel (type I), eosinophilically stained.

Dense Collagenous Connective Tissue and Intermediate Adipose Connective Tissue of the Lip

• Shows dense irregular connective tissue, venules, blood vessels, subcutaneous white adipose tissue, and nerves.

Intramembranous Ossification of Maxilla

• Illustrates bone development.
• Mesenchymal cells, osteoclasts, osteoblasts, trabeculae, and non-mineralized osteoid are components.