Duct (anatomy)

From Wikipedia, the free encyclopedia

Duct

Dissection of a lactating breast. 1 - Fat 2 - Lactiferous duct/lobule 3 - Lobule 4 - Connective tissue 5 - Sinus of lactiferous duct 6 - Lactiferous duct

Section of the human esophagus. Moderately magnified. The section is transverse and from near the middle of the gullet. a. Fibrous covering. b. Divided fibers of longitudinal muscular coat. c. Transverse muscular fibers. d. Submucous or areolar layer. e. Muscularis mucosae. f. Mucous membrane, with vessels and part of a lymphoid nodule. g. Stratified epithelial lining. h. Mucous gland. i. Gland duct. m’. Striated muscular fibers cut across.

In anatomy and physiology, a duct is a circumscribed channel leading from an exocrine gland or organ.

1 Types of ducts
2 Duct system
3 Additional images
4 External links

[edit] Types of ducts

Examples include:

[edit] Duct system

As ducts travel from the acinus which generates the fluid to the target, the ducts become larger and the epithelium becomes thicker. The parts of the system are classified as follows:

Duct	From	To	Carries
Lactiferous duct	mammary gland	nipple	milk
Cystic duct	spleen	common bile duct	bile
Common hepatic duct	liver	common bile duct	bile
Common bile duct	common hepatic duct and cystic duct	pancreatic duct	bile
Pancreatic duct	pancreas	hepatopancreatic ampulla	bile and pancreatic enzymes
Ejaculatory duct	vas deferens	urethra	semen
Parotid duct	parotid gland	mouth	saliva
Submaxillary duct	submaxillary gland	mouth	saliva
Major sublingual duct	sublingual gland	mouth	saliva
Bartholin's ducts	Bartholin's glands	Vulva	Bartholin's fluid

Type of duct	Epithelium	Surroundings
intralobular duct	simple cuboidal	parenchyma
interlobular duct	simple columnar	connective tissue
interlobar duct	stratified columnar	connective tissue

Some sources consider "lobar" ducts to be the same as "interlobar ducts", while others consider lobar ducts to be larger and more distal from the acinus. For sources that make the distinction, the interlobar ducts are more likely to classified with simple columnar epithelium (or pseudostratified epithelium), reserving the stratified columnar for the lobar ducts.