Histology - Connective Tissue - Reverse Flashcards
Abundant cells, euchromatic nuclei & with lots of cytoplasmic processes. Abundant ground substance. Few, if any, reticular fibers.
Mesenchyme
Scattered cells with heterochromatic nuclei. Fair amt ground substance. Clearly visible fibrils and fibers.
Mucous Connective Tissue
- Loose (areolar) (LCT) 2a. Dense irregular 2b. Dense regular 3. Reticular tissue
Connective Tissues Proper Types
Primarily beneath epithelium, LOTS of cells, fair amt of ground substance. Loosely arranged ECM, “woven mat”. Site of immune responses.
Loose (areolar) connective tissue (LCT)
Clear spaces, multidirectional. Fewer cells, much less ground tissue. Large bundles of collagen fibers oriented in multiple directions.
Dense Irregular Connective Tissue (DiRCT)
Fewer cells, box car nuclear arrangement, unidirectional. Little ground substance. Collagen fibers: Large bundles oriented in one direction.
Dense Regular Connective Tissue (DRCT)
Stroma of liver, spleen, bone marrow, lymph nodes, endocrine organs
Reticular Tissue Location
LOTs of cells, Meshwork of delicate specifically stained, black fibers (silver-stained). LOTs of open spaces for lymph, blood, or cells to move through. “Chicken-wire” appearance.
Reticular Tissue Features
Highly cellular, packed, surrounded by delicate ECM of reticular fibers. Not polarized or joined by tight junctions, not contractile, and do not conduct impulses. Mesenchymal origin.
Adipose tissues
Throughout body, large round oval cells, appear white. Long term energy homeostasis.
White Adipose Tissue
Multilocular adipocytes that are smaller and appear vacuolated. Heat-generation. Found mostly in infants (back, neck, shoulders) and adults around organs.
Brown Adipose Tissue
structural framework, harnesses muscle contraction into movement, scaffolding of gland and organs, medium for metabolic exchange, protection, fat storage.
Conective Tissue Support Functions
Clear, gel-like substance of varying density depending on water content that occupies the space between the cells & fibers. Usually lost with histological processing, so appears empty. Composed of Glycosaminoglycans, Proteoglycans and their aggregates, and multiadhesive glycoproteins.
Ground substance
Repeating, mostly sulfated, disaccharide units.
Glyscosaminoglycans (GAGs)
Core protein (I) + GAGs (-). Sulfated GAGs give them a high negative charge that attracts Na+ and thus water, forming a hydration shell. Present in ALL CTs, purposeof hydrating ECM.
Proteoglycans (PGs)
A core component of cartiledge ECM. Individual PG’s indirectly bound to hyaluronan (re-enforced by link protein) creating giant macromolecules that attract large volumes of water, giving ECM gel-like “shock- absorbers”.
Proteoglycan Aggregates
Charge-based filtration barrier
Primary function of GAGs & PGs in BM
Multidomain and multifunctional molecules that stabilize the ECM assembly and link it to the CT.
Multiadhesive glycoproteins (MGPs)
Fibronectin, Laminin, Tenascin, Osteopontin, Entactin/Nidogen
Multiadhesive glycoprotein examples
Elastic, Collagen, Reticular
ECM Fiber Types
Typically thinner than collagen fibers and often arranged in a branching patter. Look like “rubber bands” that have stretched then recoiled. Permit tissues to be stretched and then recoil. Found in skin, large blood vessels, lung walls.
Elastic fibers
Orcein
Specific stain for elastic fibers
Surround and permeate elastic fibers, helping to organize their growth.
Fibrillin microfibrils
Most abundant structural component (30% of dry weight of the body). Imparts tensile strength to tissues. Flexible but not elastic.
Collagen
Fibrillar (I, II, III), Sheet-forming (IV), Anchoring (VII).
Collagen types
All fibrillar collagens mature to fibril stage, but not all go on to form fibers or fiber bundles. Tropocollagen molecule to fibril to fiber to fiber bundle.
Fiber bundle assembly
mature collagen molecule
Tropocollagen molecule
orderly alignment of tropocollagen molecules
Fibril