Histology - Connective Tissue Flashcards
Embryonic CT
AKA mesenchyme
Small spindle shaped cells with a fiscous ground substance and sparse collagen fibers
i.e. mucous CT - Wharton’s jelly (hyaluronic acid and chondroitin sulfate) found in umbilical cord and vitreous humor
Connective tissue proper
Three types
Loose (aereolar) CT
Dense irregular CT
Dense regular CT
Loose CT
AKA areolar CT - found beneath epithelia and comprises the lamina propria - also surrounds the smallest blood vessels (initial site of immune response when epithelium is breached)
Dense Irregular CT
Contains mostly collagen (not much ground substance)
Typically the fibroblast/fibrocyte
Makes up the submucose of organs and the thick layer of skin (reticular dermis)
Dense Regular CT
Contains mostly collagen I fibers
Lined up in parallel arrays for max. strength (i.e. tendons and ligaments)
Cornea = DRCT (fibrocytes - keratocytes)
Tendon fibrocytes - tendinocytes
Specialized CT
Adipose, cartilage/bone, blood/marrow
What surround glandular epithelium?
Loose CT
Superior - epitendineum (thin capsule that surrounds tendon)
Inferior - endotendineum (surrounds tendon fascicles)
Extracellular Matrix
Of CT
Composed of collagen and elastic fibers (elastin and fibrillin)
Ground substance
proteoglycens (aggrecan, syndecan), adhesive proteins (fibronectin, laminin), and glycosaminoglycans (dermatan sulfate, keratan sulfate, hyaluronan)
Resident cells
Fibroblasts, myoblasts, macrophages, mast cells, adipocytes, and adult stem cells
Stationary in CT
Transient cells
AKA wandering cells:
lymphocytes, plasma cells, neutrophils, eosinophils, basophils, and monocytes
What types of collagen is required for national exams?
I, II, III, and IV
Type I collagen
Resistance to force, tension, and stretch
Comprises 90% of all collagen
Bone, tendon, ligaments, dermis, sclera, organ capsules
Type II collagen
Resistance to pressure
Cartilage (hyaline and elastic), notochord, intervertebral disk
Type III collagen
Forms reticular fibers, as a loose stromal scaffolding for parenchymal cells of many organs
Loose CT and in organs (uterus, liver, spleen, kidney, lung…etc.) smooth muscle, endonerium, blood vessels, and fetal skin
Type IV collagen
Support, filtration barrier
Basal lamina of epithelia, glomeruli, lens capsule
What synthesizes elastic fibers?
Fibroblasts and vascular smooth muscle cells
What amino acids are unique to elastin?
Desomosine and allysine (form tetramers of lysine that help cross-link adjacent elastic fibers)
Marfan’s syndrome
Autosomal dominant inheritance
Mutations in fibrillin (elastic fiber component of CT extracellular matrix)
Fibrillin
Fibrous glycoprotein that stabilizes the amorphous elastin molecules
What vessels contain elastic tissue arranged in lamina?
Large and intermediate sized arteries
Glycosaminoglycans
(GAGs) or mucopolysaccharides - polysaccharides with repeating disaccharide unites (hexose or heuronic acid linked to hexosamine)
Chondroitin/keratan/dermatan/ and heparan sulfate - exist primarily as proteoglycans
Hyaluronic acid exists only as a free GAG (thousands of sugars compared to hundreds of sugars typical with others GAGs) - allows it to hold a lot of water
Glyco
Proteoglycans
Have a core protein plus at least one O-linked GAG
Exist as monomers or as aggregates bound to hyaluronic acid
Aggrecan, decorin, versican, and syndecan
While all of the following may be be characteristic of connective tissue, which is least likely to be observed?
CT is not typically exposed to a body surface
While all of the following may be be characteristic of connective tissue, which is least likely to be observed?
CT is not typically exposed to a body surface
Which of the following is a component of reticular fibers - that is, a loose scaffolding for parenchymal cells in organs such as lymph nodes or the spleen?
Collagen type III
What collagen type is a component of reticular fibers - that is, a loose scaffolding for parenchymal cells in organs such as lymph nodes or the spleen?
Collagen type III
Multilocular vs. unilocular
Multilocular = mutliple droplets (brown fat)
Unilocular = one droplet (white fat)
Mesenchymal (embryonic) connective tissue
CT of the umbilical cord and vitreous (contains Wharton’s jelly)
Where do chodro progenitor cells reside?
The perichondrium
Predominant collagen in hyaline cartilage
Type II cartilage
ge
Elastic cartilage
Flexible and support (external ear/auditory meautus, eustachian tube, larynx)
Elastic fibers are prominent in matrix
Hyaline cartilage
Resists compression and provites structural support
Contains collagen II
Chondrocytes and chondroblasts
Fibrocartilage
Appears as a combination of dense regular CT and hyaline carilage.
Major proteins are collagen I (CT) and collagen II (cartilage)
Intervebral, articular disks
No perichonrdium
Chondrocytes and fibroblasts (instead of fibroblasts)
What causes the production of less matrix proteins of catilage in osteoarthritis?
Chondrocytes produce IL-1 and TNF - alpha, therefore, producing less matrix proteins
In certain situations cartilage can function as a shock absorber; it is pliable and compressible due primarily to the presence of ______ ?
Intercellular water
Isogenous groups of chondrocytes
Note:
H&E stain -
Capsular matrix - darkest
Territorial matrix - less
Interterritorial - even less
(Stains fibrils in matrix)
What type of proteins play the most significant role in binding extracellular water in CT?
Glycosaminoglycans
Degenerative osteoarthritis
Degeneration of articular cartilage
Plasma cell (with golgi halo)
1 - capsule matrix
2 - territorial matrix
3 - interterritorial matrix
Chondrasarcoma
Tumor in bone derived from cartilage
Sarcoma - tumor derived from connective tissue
Longitudinal section near the growth plate
Endochondral ossification
1 - Zone of reserve cartilage
2 - Zone of proliferation
3 - Zone of hypertrophy
4 - Zone of mineralization
