DEV2011 Lecture Notes - Lecture 12: Basal Lamina, Salivary Gland, Perception
25 May 2018
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Lecture 12 – Epithelial Tissues
What is an Epithelial Cell?
• Lack mobility
• Organised into closely adherent sheets – polarised in apical-basal orientation
• Derived from all 3 germ layers
• Form a barrier between outside world and body (ectoderm)
o E.g. skin
• Lining of major body cavities (mesoderm)
o Lungs, stomach, gut, some cilia
• Form glandular epithelium that surrounds glands (endoderm)
o Gastrointestinal tract
o Salivary glands, pancreas, prostate, sweat, gastric
• Functions
o Protection – skin
o Absorption – small intestine, kidney
o Secretion – small intestine, trachea
o Transport – kidney
o Sensory perception – epidermis
• Characteristics
o Polarity – apical and basal surfaces (apex, lateral and base)
▪ Basal lamina: border which epithelia rests on
▪ Lateral: epithelial cells attached to each other on lateral aspect
of cell
▪ Apical: apical surface interacts with environment (skin, gut)
• E.g. microvilli/cilia
o Specialised tight contacts between cells
o Supported by connective tissue layer
o Not vascularised (doesn’t contain blood vessels) – but are innervated
(contain nerves)
o Are able to regenerate
▪ Cut in skin, gut cell turnover
Shapes of Epithelial Cells
1. Cuboidal
• Little square boxes (tall)
• Nuclei round
• 3D cylinders
2. Columnar
• Tall shape
• Adhere to form lining
sheet of cells
• Forms surface barrier
• Found: stomach, gall bladder, intestine
3. Squamous
• Flat shape
• Nucleus is predominant
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