histopathology

• histology is the study of microscopic structural of a normal tissue or organ
• histopathology is the study of tissue in relation to diseases. Greek words: histos means tissue, pathos means disease, and logy means study of.
• histopathologic techniques involves the different processes that prepares the tissue prior to microscopic examination
• germ cells: eggs and sperm cells

  germ layers: ectoderm, endoderm, mesoderm
• four categories of tissues:

  1. connective tissues- originates from mesoderm
  2. epithelial tissues- originates from 3 combined cell layers
  3. muscle tissues- originates from mesoderm
  4. Nervous tissues- originates from ectoderm
• epithelial tissue is for protection, it lacks blood vessel (avascular) and gets nutrients from diffusion
• epthilial tissue

  1. covering epithelia

  • simple- mono or single layer
  • stratified- composed of two or more layers
  • pseudostratified- appears to have multiple layers but all cells are in contact with the cell membrane
• cellular shape of epithelial tissues:

  • squamous- flatten cell/ plate like
  • cuboidal- for secretion, cube-like
  • columnar-taller than they appear
  • transitional- they can change shape when they are stretched
• simple squamous: blood vessels, line of alveoli, bowmans capsule, loop of henle
• simple cuboidal: ducts of glands, follicles
• simple columnar:

  • ciliated: uterine tube
  • non-ciliated: gall bladder
• stratified squamous:

  • keratinized: skin
  • non keratinized: cervix, vagina, esophagus
• stratified cuboidal: ducts of sweat glands
• stratified columnar: male urethra
• transitional: urinary bladder
• pseudostratified columnar:

  • ciliated: trachea
  • non ciliated: female reproductive organs
• glandular epithelium- tissues which are involved in production of and release of secretory products in the body
• exocrine glands secretes sweat, tears, saliva, milk and digestive juices
• endocrine glands produces hormones and secretes them directly to the circulation/ blood vessels (highly vascular)
• exocrine gland:

  • tubular - stomach and uterus
  • acinar/alveolar- pancreas and salivary gland
  • tubulo-acinar- prostate gland
• methods of secretion:

  1. merocrine - there is no loss of the cytoplasm
  2. apocrine- there is only partial loss of the cytoplasm
  3. holocrine- complete or whole breakdown of the secretory cells
• connective tissue has a paucity or scarcity of cells and collagen is the abundant protein
• connective tissue differs from epithelium by the presence of abundant intercellular material called matrix
• general connective tissues:

  • loose/areolar CT
  • dense CT
  • Elastic/reticular CT
  • Adipose tissue
• general CT:

  • loose/areolar CT- BM, lymphnode, Embryo
  • Dense CT- they are strong and rope like structures
  • elastic/reticular CT- they are thick and can return to their original form
  • adipose tissue- this is for thermal insulation, storage of energy
• special connective tissue:

  • cartilage
  • bone
  • blood
  • lymph
  • hematopoietic tissue
• special CT:

  • cartilage- fibrous, hyaline and elastic
  • bone -cancellous and compact
  • cancellous- epiphysis or ends of long bones
  • compact- diaphysis or shaft-cortical
  • blood
  • lymph- lymphoid (spleen)
  • hematopoietic tissues- myeloid (bone marrow)
• collagen is the major ingredients in all connective tissues
• stains for collagen:

  • masson's trichrome
  • mallory's anilline blue
  • krajian aniline blue
  • van giessons stain
  • azocarmine stain
• pathologic changes and deposits found in CT are all eosinophilic
• fibrin results form enzymatic coagulation of plasma proteins
• fibrin stains:

  • scarlet bus
  • mallory's phosphotungstic acid and hematoxylin
  • lendrum's martus
• interpretation of fibrin:

  • early fibrin- yellow
  • old fibrin- blue
• fibrinoid has an identical staining reaction to fibrin. its the mixture of exudates and altered cytoplasmic constuituents
• PAS is the stain for fibrinoids
• stains for amyloid:

  • grams iodine stain
  • congo red
  • metachromatic staining
  • Induced fluorescence staining with thioflavine
• muscular tissue:

  • non striated
  • striated
  • involuntary
  • voluntary
• nervous tissue:

  1. central nervous tissue- brain and spine
  2. peripheral nervous tissue- peripheral nerves and cranial nerves
  3. special receptor- sense of touch, smell, hearing, sight
• muscular tissue:

  1. smooth muscle- non striated; involuntary
  2. striated muscle- striated; voluntary
  3. cardiac muscle- striated; involuntary
• histopathology is the study of abnormal tissues