Connective Tissue Cells

Question 1

What does CT consist of?

Answer 1

1. Cells

• Blasts
  
  • Undifferentiated
  • Mitotically active cells
  • Secrete Ground Substance and Fibers
• Cytes
  
  • Mature cells
  • Maintain matrix

2. ECM

• Major Constituent
• Consist
  
  • Collagen Fibers (tensile strength)
  • Elastic Fibers (Elasticity)
  • Reticular Fibers (Support loose cells)
  • Tissue Fluid
    
    • Helps remove Toxins
    • ECF- Diffusion of nutrients

Question 2

What are 2 Categories for CT Cells?

Answer 2

1. Resident Cells

• Primary Structural
  
  • Fibroblasts
    
    • Healing Process
    • Secretion of Collagen
  • Adipocytes
• Immunological Function
  
  • Mast Cells
  • Macrophages

2. Wandering Cells

• All Blood Leukocytes
  
  • Immune Defense and Inflammation
    
    • Lymphocytes
    • Monocytes
    • Neutrophils
  • Allergy and Parasites
    
    • Eosinophils
  • Release of Vasoactive agents in Response to Allergen
    
    • Basophils

Question 3

What are Fibroblasts?

Answer 3

1. Most abundant CT cell type
2. Mature
3. Active matrix secreting cells
   * During growth and wound healing
4. Nucleus
   * Stains BLUE with H&E
5. Abundant rER and Prominent Golgi

Question 4

What are Fibrocytes?

Answer 4

1. Resting Fibroblasts
2. Quiescent Phase
3. Function

• Fiber maintenance
• NOT fiber production

4. Undergo reversible changes
   * Become active and multiply for healing process
5. Stained
   * Heterochromatic (Dark Blue)

Question 5

What are Myofibroblasts?

Answer 5

1. Increase healing process

• After healing
  
  • Undergoes Apoptosis

2. Contain

• Fibroblasts
• Smooth muscle cells
  
  • Actin and Myosin isoforms

*Failure of Apoptosis

• Fibrotic disease

Question 6

What is Musculoaponeurotic Fibromatosis?

Answer 6

1. Dupuytren’s (Trigger Finger)
2. Peyronie’s Disease
3. Local proliferation of abnormal fibrous tissue
   * Contains Nodules or Plaque

Question 7

What are the different types of Macrophages?

Answer 7

1. Macrophages
   * Spleen/lymph nodes
2. Kupffer
   * Liver
3. Microglia
   * CNS
4. Osteoclasts
   * Bone
5. Histiocytes
   * CT
6. Dust Cells or Alveolar Macrophages
   * Lungs
7. Langerhans Cells
   * Skin

Question 8

What are Macrophages?

Answer 8

1. 10 to 30 µm
2. Pleiomorphic cell
3. Nucleus
   * Eccentric and sometimes oval-shaped
4. Role

• Early stages of repair
• Chronic inflammation dominated by Neurtophils granulocytes that are ingested by Macrophages
• Lysosomes
  
  • “Scavangers”

Question 9

What is Innate Immunity?

Answer 9

1. Born immunity
2. Mechanisms

• Physical barrier
• Mechanical Removal (chemicals/toxins)
• Phagocytosis

3. Operates with Leukocytes
   * T and B lymphocytes

*Involves Macrophages

Question 10

What is Adaptive Immunity?

Answer 10

1. Antigen-specific defense mechanism
2. Develops throughout life

*Involves Macrophages

Question 11

What is Humoral Immunity?

Answer 11

1. Antibody production
   * Immunoglobulin
2. Mediated by B-lymphocytes

*Involves Macrophages

Question 12

What is Cell-mediated Immunity?

Answer 12

1. Mediated by T-lymphocytes
2. Removes virus-infected cells
3. Major role in Transplant Rejection

*Involves Macrophages

Question 13

What are Giant Cells?

Answer 13

1. Multinucleated mass formed by fussion of Epithelioid cells
2. Simulus for fusion
   * Foreign body too large

Question 14

What is Foreign-body Giant Cell?

Answer 14

1. Nuclei
   * Disorganized
2. Evident

• Implants that cause the body chronic inflammation
• Ex: Breast Enlargements

Question 15

What is Langhans Giant Cell?

Answer 15

1. Nuclei

• Arranged in cell periphery
• “Horseshoe-shape”

2. Large cell in Granulomatous conditions

Question 16

What is Touton Giant Cells?

Answer 16

1. Nuclei
   * Form ring surrounding foamy cytoplasm
2. Seen in High Lipid Content

• Fat necrosis
• Xanthoma
• Xanthogranuloma

Question 17

What are Mast Cells?

Answer 17

1. 20 to 30 µm in diameter
2. Cytoplasm
   * Granulated due to Secretory Vesicle
3. Metachromasia
4. Nucleus

• Spherical
• Basophilic

5. Location

• Near blood vessels in
  
  • CT
  • Mucosa of Respiratory and GIT

Question 18

What are Secretory Granules?

Answer 18

1. Contain

• Heparin
  
  • Sulfated GAG
    
    • Anticoagulant
• Histamine
  
  • Promote Vacular permeability and Smooth muscle contraction
• Serine Proteases
  
  • Activate mediators of inflammation
• Cytokines, polypeptides
  
  • Immune system
• Phospholipids Precursors
  
  • Converted to Prostaglandins
  • Lipid mediators

Question 19

What is the relationship between Mast Cells and Allergens?

Answer 19

1. Mast cell surface contain IgE receptors
2. Causes

• Type 1 Hypersensitivity Reaction
  
  • Condition
    
    • Asthma
    • Allergic rhinitis
    • Conjunctivitis
    • Cutaneous hives
    • Anaphylactic shock

Question 20

What are Lymphocytes?

Answer 20

1. Second most common WBC
2. 7 to 9 µm in diameter
3. Cytoplasm

• Non-granular
• Pale BLUE staining

4. Nucleus

• Large, round, basophilic
• Heterochromatic staining

5. Numerous in Lamina Propria

Question 21

What is B Lymphocytes?

Answer 21

1. Short-lived
2. Circulate in an immature form
3. Mature in Bone Marrow

Question 22

What is T lymphocytes?

Answer 22

1. Precursors of T cell (leave bone marrow)

• Killer T cell
• Helper T cell
• Treg (T-regulatory cell)

2. Mature in Thymus
3. Involved in
   * Cell-mediated Immunity

Question 23

What are Plasma Cells?

Answer 23

1. Tissue resident form of B lymphocyte
   * Differentiate into Plasma cells
2. Large Ovoid Cells
3. Nucleus

• Spherical
• Chromatin distribution
  
  • Dense Chromatin (“Cart Wheel” or “Clock-face” appearance)

4. Function
   * PRODUCTION OF ANTIBODIES
5. Location

• Lymphoid organs
• Loose CT