General Histology

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General Histology

• Epithelium
• Blood

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Fertilization formation of zygote
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Cleavage becoming multicellular
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Gastrulation fomation of 3 primary tissues
ectoderm, endoderm, mesoderm
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Tissues of adult organism

• A tissue is defined as a group of similar cells
  with their extracellular products, specialized in
  common direction and set apart for the
  performance of a common function
• About 200 types of specialized cells in adult
  human body are arranged into 4 main tissues
• Epithelium
• Blood and connective tissues
• Muscular tissues
• Nervous tissues
• Tissue formation is called Histogenesis
• Tissues are studied in General Histology course

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Epithelium
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Epithelium hallmarks

• Epithelium covers body surfaces, lines body
  cavities, and constistutes glands, therefore it
  is subdivided into lining and glandular
• Epithelium creates a selective barrier between
  the external environment and the underlying
  connective tissue
• The cells predominate, they are closely apposed
  and adhere to one another by means of special
  junctions
• Their basal surface is attached to an underlying
  basement membrane
• Apical surface may contain nicrovilli and cilia

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Classification of lining epithelia
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Location of different types epithelium

• SIMPLE Lining of vascular system
• SQUAMOUS Lining of body cavities
• Bowmans capsule
• Lining of lung
  alveoli
• SIMPLE Small ducts of exocrine
  CUBOIDAL glands
  
• Surface of ovary
• Kidney tudules
  

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Location of different types epithelium

• SIMPLE Lining of small intestine
  
• COLUMNAR and colon
• Stomach and gastric
  glands
• Lining of gallbladder
• PSEUDO- Lining of trahea and bronchi
• STRATIFIED Lining of ductus deferens
• Efferent ductules of
  
  epididymis

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Location of different types epithelium

• STRATIFIED Epidermis
• SQAMOUS Lining of oral cavity and
  esophagus
• Lining of vagina
• STRATIFIED Sweat glands, ducts
• CUBOIDAL Lager ducts of exocrine
  glands
• Anorectal junction

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Location of different types epithelium

• STRATIFIED Largest ducts of exocrine
• COLUMNAR glands
• Anorectal junction
• TRANSITIONAL Renal calyces
• Ureters
• Urinary bladder
• Urethra

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Specialized surfaces of epitheliocytes

• Apical specializations
• - microvilli and cilia
• Lateral specializations
• - zonulae occludentes
• - zonulae adherentes
• - maculae adherentes
• - gap junctions
• Basal specializations
• - hemidesmosomes
• - basal striations

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Microvilli and terminal web
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Structure of a cilium
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Electron micrographs of cilia
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Lateral specializations of epitheliocytes
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Classification of glands
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Multicellular exocrine glands classifiication
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Modes of secretion A holocrine B
merocrine C - apocrine