Table 1.

Types of epithelial cells present in specific hollow organs.

Organ	Epithelium type	Function	References
Trachea	Many cell types within epithelium: Ciliated pseudostratified columnar Secretory goblet Serous cells Basal neuroendocrine cells Basal stem cells	Moisten and protect airways Barrier to pathogens Mucociliary elevator	Delaere and Van Raemdonck10
Oesophagus	Stratified squamous	Rapid turnover Protective barrier function against the abrasive effects of food	Ozeki et al.11, Kalabis et al.12
Stomach	Stratified squamous above cardia Simple columnar with gastric pit invagination below cardia	Mucus cells produce protective alkaline mucus to prevent digestion of stomach wall from HCl producing cells	Young et al.13
Small Intestine	Simple columnar (enterocytes, goblet cells, enteroendocrine cells, M cells and Paneth immune cells)	Selectively absorb digested material from intestinal lumen Release mucus Barrier to pathogens	Day14
Urinary Bladder	Referred to as urothelium Transitional Basal layer: compact and cuboidal Intermediate: columnar Surface cells: dome cells which are imperbeable to urine	Epithelium can contract and expand in response to volume of bladder: allows bladder to change shape according to volume of urine without damaging epithelium Protects underlying tissue from caustic effects of urine Protect blood–urine barrier	Liao et al.15
Urethra Prostatic Membranous Penile	Referred to as urothelium Transitional Pseudostratified columnar/stratified squamous Pseudostratified columnar	Mucus-secreting cells to protect underlying tissue from urine Protect blood–urine barrier	Liao et al.16