Flashcards in Lecture 11: Connective Tissue II Deck (8):
Fibroblasts and fibrocytes are the principal cell types found in connective tissue. They are also the most numerous cells found in CT.
- Secretion and maintenance of CT matrix.
- Secretion of precursor fibrous molecules.
- Secretion of the amorphous components of the matrix, including the glycosaminoglycans.
- Review Tissue on Slide 5
What other cells are found in fibrous CT besides fibroblasts and fibrocytes?
Common types of cell residents include:
- Mast cells
- Plasma cells
- 10 –30 μm.
- Ovoid or indented heterochromatic nucleus. (Dark Spots)
- Irregular in shape with blunt processes:
-- Wandering macrophages are somewhat oval in shape.
-- Fixed macrophages are more irregular in shape with long processes.
- Capable of amoeboid movement
- Part of mononuclear phagocytic system (originally called the reticular activating system –RAS).
- Extensive Golgi, rER, sER, mitochondria, secretory vesicles, and lysosomes.
- May fuse with other macrophages to form large multinucleated phagocytic foreign body giant cells.
Where are macrophages found?
- Wandering in blood (monocytes)
- Connective tissue (histiocytes)
- Liver sinusoids (Kupffer cells)
- Sinusoids of spleen, lymph nodes, bone marrow (perialveolar macrophages)
- Alveoli of lungs (dust cells)
- Central nervous system (microglia)
- Associated with bone reabsorption (osteoclasts)
- Review Slide 10
Describe the structure Mast Cells
- Irregularly oval in outline.
- Small spherical/ovoid nuclei often masked by membranebound granules.
- Stain with toluidine blue.
- Large metachromatic granules with histamine, ECF-A, SRS-A, and heparin.
- ECF-A (eosinophil chemotactic factor) attracts eosinophils and neutrophils.
- SRS-A (slow reacting substance of anaphylaxis) similar to histamine but has a more sustained effect.
- Heparin from mast cells is a poor anticoagulant and is probably involved in helping clear plasma lipids.
What effects do mast cells have to allergens?
Where are mast cells found?
- Involved in hypersensitive response to allergens: Edema, Shock, Pain, Hypercoagulation, Fever
- In reaction, the membranes release leukotrienes.
- They're Found near small blood vessels:
- Target of histamine and SRS-A.
- Absent from spleen.
- Found in mucosal surfaces and in connective tissues.
- Review Tissue on Slide 14
Describe Plasma Cells
- Activated B lymphocytes.
- Resemble lymphocytes but are larger.
- Large pale nuclei with “clock-face” distribution of heterochromatin.
- Spherical and typically offset
- Prominent Golgi and extensive RER.
- Rare in connective tissue.
Frequently occur in: Serous membranes, Lymphoid tissue, and the Lamina propria of gut tract
- Review cell on slide 17