Hhis

• Pseudostratified epithelium appears to be in several layers
• Components of a microscope

  • Framework
  • Stage
  • Mechanical stage
  • Mechanical control
  • Stage clip
  • Aperture
  • Light source/illuminator
  • Voltage regulator
  • Neutral density filter
  • Diopter adjustment ring
  • Ocular/eyepiece
  • Objectives
  • Condenser
  • Iris diaphragm
  • Revolving nosepiece
  • Coarse adjustment
  • Fine adjustment
• Histology is the study of tissues of the body
• Types of light microscopy

  • Brightfield
  • Fluorescence
  • Phase-contrast
  • Darkfield
• Magnifications of different objectives

  • Scanner - 4x magnification
  • LPO - 10x magnification
  • HPO - 40x magnification
  • OIO - 100x magnification
• Histology

  Comes from the Greek word “histos” (tissue or columns) and “logia” (study)
• Epithelial tissue classifications

  • According to number: single or compound
  • According to shape: squamous, cuboidal, or columnar
  • According to specializations: cilia, keratin, or goblet cells
• Parfocal objectives can be changed with minimal to no refocusing
• Goblet cells

  Nuclei is surrounded by RER, GOLGI COMPLEX, and SECRETORY GRANULES
• Steps in preparing tissue for microscopic examination

  • Fixation
  • Dehydration
  • Clearing
  • Infiltration
  • Embedding
  • Trimming
  • Staining
  • Mounting and labelling
• Total magnification is calculated by multiplying the ocular lens magnification by the objective lens magnification
• Stratified squamous epitheliu
• Hemidesmosomes

  Major junctional complex of the basement membrane
• Adherent junction protein

  • E-cadherin and catenin complexes
• Desmogleins


  • Error of coding
• Nutrients for epithelial cells diffuse across the basement membrane
• Reticular fibers consist mainly of collagen III
• Metaplasia is the step before cancer, the body's natural way to adapt when injuries occur
• Microvilli


  Prominent brush border in the lumen that facilitates reabsorption
• Adherent junction

  Main function is to link cells
• All epithelial cells are avascular
• Desmocollin

  • Links the cytoskeleton to the basement membrane
• Tight junction


  Controls the passage of solute and solvent and seals cells from one another
• Paracrine hormones diffuse into the blood for circulation and bind specific receptors on target cells
• Cilia

  Larger projecting structure with a well-organized core of microtubules
• Types of epithelial coverings

  • Mesothelium
  • Endothelium
  • Myoepithelium
  • Endometrium
  • Germinal epithelium
  • Glandular epithelium
• Mitosis is an essential process, cell division that produces two sister
• Collagen fibers are the most abundant protein in the human body
• Glycoamino glycans (GAGs) are for cell adhesion, proliferation, growth, and wound repair
• Gap junctions


  Channels for communication between adjacent cells
• Fibronectin aids in the attachment of cells in the epithelial tissues
• Types of glands

  • Unicellular gland
  • Multicellular gland
  • Exocrine gland
  • Endocrine gland
• Cytoplasmic organelles

  • Plasma membrane
  • Mitochondria
  • Ribosomes
  • Lysosomes
• Laminin is used by epithelial cells to adhere to the basement membrane
• Connective tissue fibers

  • Collagen fibers
  • Reticular fibers
  • Elastic fibers
• Perlecan + GAGs + collagen = basal lamina for basement membrane
• Multiple adhesive glycoproteins are for the adhesion of cells
• Proteoglycans support GAGs and modify their functions
• Components of cytoskeleton

  • Microtubules
  • Microfilaments
  • Intermediate filaments
• Keratin is seen in the skin and is known to prevent water loss