MSK CNT Flashcards
What are the major determinants of the functional and histological characteristics of a given connective tissue?
- orientation
- volume of fibers
- ratio of fibers to ground substance
What are the three types of connective tissue?
- Embryonic CT
- Adult CT
- Special CT
(connective tissue is one of the 4 main tissues of the body: CT, epithelium, muscle, nerve)
Define Proteoglycan
Molecule with core protein with bound GAGs (glycosaminoglycans)
What are the noncellular componenets of CNT?
- ground substance: jelly-like, highly hydrated
- GAG (glycosaminoglycans)
- proteoglycans
- hyaluronic acid
Define hyaluronic acid. Where is it found?
- Unique GAG that attaches proteoglycans.
- non-cellular ground substance (synovial fluid, vitreous humor, cartilage)
(highly viscous in aqueous solution)
What are 2 major CNT proper ground substance glycoproteins?
- fibronectin
- laminin
(adhesive glycoproteins found in the BL)
What is the most common CNT fiber?
Collagen
(30% of the dry weight of the body)
What is the most abundant type of collagen?
Type 1
(acidophilic; stain pink,
Describe Collagen type III.
- small fibril associated with type I
- constituent of reticular CNT
- held together by proteoglycans and glycoproteins
What are the histological staining characteristics of collagen type III?
- reticular fibers (do not stain with H&E)
- argyrophilic (bind silver salts)
- distinct black fibers in silver impregnation prep
Histological characteristics of elastic fibers?
- poorly stained w/conventional methods
- can be stained purple black w/Orcein
Where is elastic tissue found?
- skin
- earlobe
- ligaments between vertebrae
What is the tissue stained at the arrow?
Elastic fibers
Elastin is synthesized by______.
- fibroblasts
- smooth muscle
(Marfan’s syndrome is due to the mutation of fibrillin gene, leading to weakening of vascular walls)
What are the cellular componenets of CNT?
- fixed cells: fibroblasts and mast cells
- transient cells: plasma cells & leukocytes
- macrophages (fixed and transiet)
- mesenchymal cells (embryo only)
(fixed develop in & stay in the CNT)
Where do most resident CT cells arise from?
mesodermal mesenchyme cells (embryo)
What is the most common cell in the CNT proper?
Fibroblast
Describe the fibroblast
elongated
spindle or stellate-shaped
pale
ovoid nucleus
well-developed ER & GA
(when active)
What cell synthesizes elastic fibers, reticular fibers and collagen?
Fibroblast
(they produce much of the CNT ground substance)
What is the most abundant form of adipose in adults
unilocular cells (white adipose cells)
Primary energy source in the body. Adipose has a higher proportion of cells than EC CNT fibers or ground substance.
What cell type makes up the brown fat? What are their unique characteristics?
- multilocular adipose cells
- smaller than white/unilocular cells, tissue is brown due to more mitochondria. mostly found in embryos and infants
What are the histological characteristics of mast cells?
- small, round, central nucleus
- granules in cytoplasm
- appear violet (basophilic in H&E & Metachromatic w/toluidine blue)
Describe the histologic characteristics of macrophages.
kidney-shaped nucleus
pseudopodia
basophilic cytoplasm
Where do the monocytes develop and reside?
- bone marrow
- migrate into CNT where they become macrophages
What are the functions of macrophages?
ingestion of debris, dead cells, and invading microorganisms followed by breakdown of the ingested matter with lysosomal enzymes.
Describe the shape, nucleus and unique characteristics of plasma cells.
Well-developed RER
basophilic stain
round, eccentric, clock-face nuclei
What are the unique characteristics of embryonic CNT?
blends into collagen fibers
oval nucleus
pale cytoplasm
numerous processes
Histological characteristic of reticular fibers
black “webbing” with cells interspersed in silver-stained prep
(LN=lymph node)
3 categories of Dense CNT?
- dense irregular
- dense regular collagenous (tendons & ligaments)
- dense regular elsatic
Where is dense irregular tissue found?
mostly the dermis of the skin
organ capsules
large nerves
Describe dense regular CNT (DRCCT) found.
- thick, densely-packed bundles of collagen
- arranged in parallel cylinders or sheets
Describe organization of dense regular elastic CNT.
thick, branching elastic fibers
arranged in parallel arrays
(found in blood vessels and ligaments between vertebrae)
