Tissue and Other Levels of Organization: Animal and Epithelial Tissues

Doorsteptutor material for GATE is prepared by world's top subject experts: fully solved questions with step-by-step explanation- practice your way to success.

Download PDF of This Page (Size: 246K)

Animals are various types which perform different functions and are types as under.

Image showing types of animal tissues.

Image Showing Types of Animal Tissues

Epithelial Tissue

  • Location: continuous layer over the free surfaces of many other tissues and it covers the external surfaces of the animal body and the internal surfaces of visceral organs, body cavities and blood vessels.

  • Structure: consists variously shaped cells, arranged in single or multilayered sheets, are closely packed with no intercellular space in between and arise from a non-cellular basement membrane. Epithelial cells possess the power of division and regeneration, blood vessels are absent, and the free surface of cells may be smooth or may have fine hair-like cilia, stereocilia and microvilli.

  • Function: Protects the underlying or overlying tissues from the mechanical injury, entry of germs, drying up and harmful chemicals and also help in absorption, secrete and also bear protoplasmic projections such as the Cilia.

Types of Epithelial Tissue

Types of Epithlial Tissue
Types of epithlial tissue





Squamous Epithelium

Thin, flattened and contain little cytoplasm enclosing centrally placed disc nuclei and margins of cells are tessellated (irregular)

Lining of lungs alveoli, blood vessels and Bowman’s capsule of the kidney

Diffusion of material or exchange of gases O2 and CO2

Cuboidal Epithelium

Cells are cube-shaped and possess a central spherical nucleus. Cells are either pentagonal or hexagonal (polygonal)

Lining of many ducts such as salivary, pancreatic and collecting ducts of the kidney

Secretion, excretion and absorption

Brush-bordered cuboidal epithelium

Cells of cuboidal epithelium in absorptive surfaces bear microvilli on their free ends and gives a brush like appearance to their border, so it known as this name

Proximal convoluted tubules of nephron

Microvilli greatly increase the area of the free surface of the cells and thereby absorption

Ciliated cuboidal epithelium

Cilia on the free surface, associated with secretory goblet cells.

Parts of the nephron

Flow of nephric filtrate

Ciliated Epithelium

Bear numerous cilia at their free surfaces

Lining of the hollow organs such as ovi-ducts, ventricles of the brain, the spinal canal and the respiratory passages

To move particles, free cells in a specific direction over the epithelial surface

Columnar epithelium

Cells are tall and quite narrow, nucleus is usually located at the base

Lining of stomach, intestine, and gall-bladder, also present in gastric and intestinal glands

Secretion or absorption

Ciliated Columnar Epithelium

Cilia at free end. Mucus secreting goblet cells in between

Respiratory passage (bronchioles), oviducts and spinal canal

Flow of fluids in a particular direction

Brush bordered Columnar Epithelium

Microvilli at the free ends

Intestinal mucosa

Increase surface area for nutrition

Pseudo-stratified epithelium

Made up of single layer of columnar cells, appears two layered because shorter cells have their nuclei at a different level, shorter cells lack cilia while longer cells are ciliated

Lining of urinary tract, the trachea, other respiratory passages and as component of olfactory mucosa

Secretes mucus which traps bacteria and particles on the epithelial surface. The ciliary beat expels the bacteria and particles in the outward direction

Image showing types of epithelium.

Image Showing Types of Epithelium

If the epithelial cells are in a single layer, they form simple epithelium. If the epithelial cells are arranged in many layers, they form compound epithelium. Compound epithelium have little role in secretion and absorption and provides protection to underlying tissues against mechanical, chemical, thermal or osmotic stresses. Compound epithelium may be stratified and transitional.

Developed by: