General Histology
Epithelium
Blood
Fertilization: formation of zygote
Cleavage: becoming multicellular
Gastrulation: fomation of 3 primary tissues –
ectoderm, endoderm, mesoderm
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
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
SQUAMOUS
Lining of vascular system
Lining of body cavities
Bowman`s capsule
Lining of lung alveoli
SIMPLE
CUBOIDAL
Small ducts of exocrine
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
PSEUDOSTRATIFIED
Lining of trahea and bronchi
Lining of ductus deferens
Efferent ductules of
epididymis
Location of different types epithelium
STRATIFIED
SQAMOUS:
Epidermis
Lining of oral cavity and
esophagus
Lining of vagina
STRATIFIED
CUBOIDAL:
Sweat glands, ducts
Lager ducts of exocrine
glands
Anorectal junction
Location of different types epithelium
STRATIFIED
COLUMNAR:
Largest ducts of exocrine
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