Connective+Tissues+Lab


 * 1 September 2006**
 * Microanatomy Lab – Connective Tissues Lab**
 * Dr. Robert Crissman, Ph.D.**

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=**Embryonic Connective Tissue**=


 * Mesenchyme Tissue
 * Scattering of well separated cell
 * Relatively acellular with lots of ground substance
 * Diagnostic Characteristics:
 * Cells are well spaced apart allowing other cells to migrate
 * Cells are still relatively close, tending to clump together compared to Mucoid CT
 * Fixed cell types are likely mesenchyme cells
 * Predominate fibers are probably collagen I

=**Umbilical Cord**=


 * Contains 3 blood vessels:
 * 2 arteries and 1 vein
 * Thin periphery “skin”
 * All the rest of the tissue is mucoid connective tissue
 * Function – carry blood and nutrients to fetus and waste products back
 * Don’t want it to kink
 * Put lots of proteoglycans which pull water, creating a slippery gel-like tension in the tissue
 * Allows umbilical to bend (still flexible) but hard to kink like a hose on pressure
 * Diagnostic characteristics:
 * In reality, there aren’t extracellular fibers
 * Really participated proteoglycans like hyaluronic acid
 * Cells much more distantly spaced apart than in mesenchyme

=**Omentum**=


 * Loose or Areolar CT
 * This slide is stained for elastic fibers (not typically stained)
 * Diagnostic characteristics
 * Scattered cells
 * Fibroblasts secrete fibers
 * Mast cells, eosinophils and macrophages probably there but can’t be distinguished because the stain doesn’t stain the cytoplasm and nuclei identification is not possible
 * Elastic fibers
 * Acute angle of intersection, very thin
 * Form a branching network but don’t branch themselves
 * Collagen fibers also present
 * Wide, unbranched straight fibers gathered in bundles
 * Fibers going in all directions (irregular) because it is unclear where the stress might be coming from

=**Trachea and Esophagus**=


 * Plasma cells present in loose connective tissue
 * Diagnostic characteristics
 * Cartwheel nucleus pattern
 * Eccentrically located nucleus
 * Plasma cells are derived from B cells

=**Auxiliary Skin**=


 * Epithelium
 * Keratinized stratified squamous
 * Glands
 * Simple cuboidal
 * Surrounded by loose CT
 * Less dense fibers, more cell nuclei than dense irregular CT
 * Loose CT to allow glands to expand when secreting
 * Elastic Fibers
 * Allow dermis some stretch
 * Very dark staining but have acute intersections

=**Adipose Tissue**=


 * White adipose cells
 * Signet ring appearance due to unilocular appearance
 * Single lipid droplet

=**Heart**=


 * Brown fat cells
 * For heat generation
 * Multilocular
 * Several lipid droplets in a cell
 * Most of it disappears in the first year of life

=**Tendon**=


 * Dense regular CT
 * Collagen fibers Type I with nuclei of fibroblasts throughout fasicle
 * Fibroblasts are very flat looking, stellite in shape
 * No cytoplasm visible
 * Tendons don’t have a good blood supply
 * Take a long time to repair
 * Muscle cells would have nuclei at the periphery and be striated
 * **Collagen is for strength**
 * Identify the tissue: dense regular connective tissue
 * Identify the organ: tendon or ligament
 * Tendon – muscle to bone
 * Ligament – bone to bone

=**Liver**=


 * Reticular fibers
 * Type III collagen (sugar coated)
 * Diagnostic characteristics:
 * Right angle intersections of interconnecting fibers
 * Squiggly, fairly short
 * Dark staining (silver)
 * Probably hard to find a reticular cell
 * Nuclei are wandering cells (macrophages, lymphocytes, plasma cells)

=**Ligamentum Nuchae**=


 * Elastic fibers
 * Branches in acute angles
 * Surrounded by amorphous ground substance and some collagen
 * Nuclei are fibroblasts

=**Aorta**=


 * Elastic CT
 * Individual sheets of elastic fibers
 * Interconnected by finer elastic fibers in between
 * Collagen fibers are also found in between
 * In this case, extracellular fibers secreted by the smooth muscle cells