Microanatomy Connective Tissue Flashcards
What are the main divisions of connective tissue, and their subdivisions?
Embryonic: Mesenchyme and mucous CT.
CT proper: Loose and dense
Specialized: Reticular, adipose
Describe collagen type 1.
Most abundant.
Produced by fibroblasts and exists in CT proper.
In dermis, ligament, tendon, bone, and cornea.
Describe collagen type 2.
Resides in elastic cartilage and hyaline.
Is produced by chondrocytes.
Exists as thin fibrils, not thick fibers like collagen 1.
Describe collagen type 3.
Are reticular fibers that form a mesh work to support soft organs.
Also exists in basal lamina underneath epithelia.
Are highly glycosylated and PAS positive too.
Produced by fibroblasts, reticular cells, Schwann cells, and smooth muscle cells.
Describe collagen type 4.
Exists in the lamina densa.
Do not form fibrils as pro peptides at end of molecule are not removed.
Form a mat-like structure.
Describe collagen type 7.
Exists in lamina reticularis.
Function as anchoring fibrils to link epithelia of skin to the lamina densa.
Where do elastic fibers reside?
In tissues that stretch often such as dermis, arteries, vocal cords, and bladder.
What are the structures of elastic fibers?
Thin fibers within a sheath of fibrillin.
As fenestrated sheets in arteries.
What is the ground substance composed of?
- GAGs
- Glycoproteins
- Tissue fluid
Describe the GAGs. What feature do they impose on the ECM?
Long and inflexible polysaccharide chains bound to a core protein in a bottle brush formation due to their highly negative charge (sulfation).
Due to being highly hydrated, they give ECM a gel like consistency.
Describe the glycoproteins.
Are adhesive portions of the ground substance to promote attachment of cells to ECM, and one ECM component to another.
Main ones are fibronectin from fibroblasts and laminin of the basal lamina (binds epithelial cells to basal lamina via transmembrane proteins and collagen/GAGs, respectively).
How are fibroblasts best identified?
Flattened nuclei
Inactive: flattened/wispy cell
Active: distended and irregular ER if actively secreting protein (look like blebbing, but PM is intact), nucleus is more round but spider web like cytoplasmic processes still exist.
How are macrophages identified?
A very irregular PM and nucleus, high amounts of phagocytic vacuoles and secondary lysosomes, nucleus is euchromatic.
What does herapin from mast cells and basophils cause?
Anticoagulant activities.
How can a mast cell be differentiated from other cells?
Highly present secretory granules throughout the cytoplasm that are large enough to distinguish them from eosinophils, and nucleus is surely nonlobed distinguishing it from basophils.
