Expansion
Unicellular mucous glands, increasing distally along the gut
Expansion
Structure: a unicellular mucous gland, shaped like a goblet with a narrow base containing the nucleus and rough endoplasmic reticulum, and an expanded apex packed with mucinogen granules. Stains strongly with PAS and alcian blue.
Distribution
- Respiratory tract: numerous in the trachea and bronchi, absent from the terminal bronchioles onwards, where club (Clara) cells take over
- Gastrointestinal tract: increase in number distally, being few in the duodenum and most numerous in the colon
- Absent from the stomach, where surface mucous cells secrete mucus instead
Clinical relevance
- Goblet cells in the oesophagus are abnormal and define intestinal metaplasia, which is Barrett’s oesophagus, the precursor to adenocarcinoma
- Goblet cell hyperplasia in the airway causes the excess mucus of chronic bronchitis, asthma and cystic fibrosis
- Depletion of goblet cells is a feature of active ulcerative colitis, and their regeneration marks healing
Mucus has two functions: a physical and chemical barrier over the epithelium, and, in the airway, the gel phase of the mucociliary escalator, riding on the sol phase in which the cilia beat.