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General Histology
EpitheliumBlood
Fertilization: formation of zygote
Cleavage: becoming multicellular
Gastrulation: fomation of 3 primary tissues – ectoderm, endoderm, mesoderm
Tissues of adult organismA 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
Epithelium
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
Classification of lining epithelia
Location of different types epithelium
SIMPLE Lining of vascular system
SQUAMOUS Lining of body cavities
Bowman`s capsule
Lining of lung alveoli
SIMPLE Small ducts of exocrine CUBOIDAL glands
Surface of ovary
Kidney tudules
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
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
Location of different types epithelium
STRATIFIED Largest ducts of exocrine
COLUMNAR: glands
Anorectal junction
TRANSITIONAL: Renal calyces
Ureters
Urinary bladder
Urethra
Specialized surfaces of epitheliocytes
• Apical specializations:
- microvilli and cilia• Lateral specializations:
- zonulae occludentes
- zonulae adherentes
- maculae adherentes
- gap junctions
• Basal specializations:
- hemidesmosomes
- basal striations
Microvilli and terminal web
Structure of a cilium
Electron micrographs of cilia
Lateral specializations of epitheliocytes
Classification of glands
Multicellular exocrine glands classifiication
Modes of secretion: A – holocrine; B – merocrine; C - apocrine