MCM 2-28 Microanatomy of Connective Tissue Flashcards
definition of connective tissue
functions?
examples?
tissue that forms a continuum with the other 3 major tissues to maintain a functionally integrated body
mostly structural. characterized on basis of its ECM
organ capsules, tendons/ligaments, areolar tissue filling spaces, fat, cartilage, bone.
connective tissue develops from
embyronic mesenchyme, which forms from embryonic neural crest
embyronic neural crest -> embryonic mesenchyme -> connect tissue
describe mesenchymal appearance
what can they function as in adult tissue?
oval nucleus, prominent nucleoli, small amount of cytoplasm
stem cells
if a cell has lots of euchromatin
it is replicatively/synthetically active
connective tissue has two components
ECM - ground substance, protein fibers, tissue fluid (blood/plasma)
and connective tissue cells (resident and immigrant) CT cells
resident CT cells
arise in CT, spend entire life there
create the fibers and ground substance of CT, along with adipocytes
mesenchymal cells, fibroblasts, fibrocytes, reticular cells, adipocytes
immigrant CT cells
arise in hematopoetic bone marrow stem cells, migrate into the CT
macrophages, mast cells, plasma cells, leukocytes, eosiniphils (lots of cells from bone marrow)
-cyte?
blast?
cyte is a more mature form
blast is a cell that prolfierates and gives rise to other cells
fibroblast appearance
euchromatic nucleus, lightly stained
lots of organelles in cytoplasm
fibrocyte role and appearance
focused on secretion of collagen and ground substance. no longer proliferating
nucleus is more condensed heterochromatin, not the active euchromatin-like fibroblast.
blasts vs cytes
blasts - highly euchromatic nucelus, packed with organelles (golgi, ER) and irregular shaped
cytes - spindle shaped, heterchromatic necleus, fewer organelles, embedded within matrix.
reticular cell role and appearance
fibroblast like cells that produce reticular fibers in hematopoietic, lymphoid, and adipose tissue
stellate shaped cells with oval euchromatic nucleus that has prominent nucleolus
adipocytes
single lipid dropet that pushes cytoplasm and nucleus to the periohery (signet ring cell).
brown (multilobular) and white (unilobular)
describe macrophages
apperance?
how do we ussualy idenfity?
monocytes travel in blood and migrate into CT to form macrophages
smaller than fibroblast, heterochromatic KIDNEY SHAPED nucleus and cytoplasm filled with granules. Dark heterochromatin ring around periphery. lots of lysosomal vacoules
idenfity in animals by injecting trypan blue (colloid dye)
Mast cells
largest of CT cells
cytoplasm filled with membrane-bounded basophilic granules that contain heparin, chondriton sulfate, and ECF-A
allergic reactions, found around blood vessels
light colored cytoplasm with darker central nuclues
plasma cells
differentiate from antigen stimulated B-cell
large, ovoid cells
eccentric nucleus, abundant RER, “CLOCK FACE” nucleus, clear zone near nucleus contains golig and centrioles
ground substance description
consists of?
functions as?
viscous mixture that binds cells to CT fibers
consists of GAGS, proteoglycans, and multiadhesive glycoproteins (lamin and fibronectin)
functions are both structural and physiological - homrones and growth factors have resovoirs in GS
CT fiber types
collagen - >50nm fibrils, 1-20 micron fibers. Thickest
Reticular fibers -
describe collagen type 1 (exam q)
forms triple helix, when bind to one another, form 64 periodicity. striped. form tendon
most widespread, most abundant protein in the body (90%). resists tension like in tendons
collagen 3
forms reticular fibers, flexible meshwork
collagen 2
cartilage, resists pressure
collagen 4
important component of basal lamina
collagen 7
anchores basement membrane to collagen fibers
basal lamina vs basement membranes
BL - lamina lucida and lamina densa
bm = basal lamina + reticular fibers
Osteogensis Imperfecta
single nucleotide change in collagen I gene
produces aortic rupture, fractures
Scurvy (vitamin C deficiency)
impaired wound healing, issues with collagen synthesis due to lack of vitamin c
Ehlers-Danlos type IV
type III collagen problem
aortic/intestinal ruptures
Marfan syndrome
mutant fibrillin, elastin core can overstretch, danger of blood vessel rupture
CT fiber staining
collagen -
reticular -
elastic -
collagen - pink in H&E
reticular - pink in H&E, indistinguihsable form collagen without silver stain
elastic - pink in h&e, not distinguishable from collagen without resorcin-fuschin or picro-orcelin
Loose areolar CT
found where?
characteristics?
located where?
found in intervening spaces
more cellular than dense CT
lots of resident cells
found in lamina propria, mesentary, and pappilary layer of dermis
positioned between tissues to allow movement
Dense Irregular CT
more fibers than cells
fibers interwoven
found in organ capsules, reticular layer of dermis, periosteum
Dense Regular CT
longitudinal section?
more fibers than cells
fibers in parallel bundles or sheets
tendons, ligaments, cornea
in longitudinal section - nuclei of fibrocytes look like dashes, lots of collagen in one direction
describe reticular CT
mesh of fibers, stain with silver, filled with lymphocytes
adipose tissue
CT with special properties
“chickenwire fence”
highly vascular (single file red blood cells)
mesenchymal cell to adipoctyte progression
mesenchymal cell -> fibroblast or lipoblast
lipoblast -> multiocular adipocyte (brown) or uniocular adipoycte (white)
why is brown fat “brown”?
packed wtih mitochondria, cytochromes within mitochondria give brown tinge
most common CT cell?
fibroblasts
can serve as stem cells in adult tissue
mesenchymal cells
vitally stained with tryphan blue
macrophages
derived from b lymphocytes
plasma cells
secrete antibody
plasma cells
often found around venules
eosinophils
have heparin containing granules
mast cells
selectively stained by silver
reticular fibers
allow stretch and recoil of blood vessels
elastic fibers
composed of type III collagen
reticular fibers
composed of type I collagen
collagen fibers
most abundant fiber type in lymphoid tissues
reticular, I think.
contain the amino acids desmosine and isodesmosine
elastic fibers
fomr the largest diameter fibers in loose CT
collagen fibers
