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.
Types of ducts
|Lactiferous duct||mammary gland||nipple||milk|
|Cystic duct||gallbladder||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|
|Submandibular duct||submandibular gland||mouth||saliva|
|Major sublingual duct||sublingual gland||mouth||saliva|
|Bartholin's ducts||Bartholin's glands||vulva||Bartholin's fluid|
|Cerebral aqueduct||fourth ventricle||third ventricle||cerebrospinal fluid|
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:
|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.
Section of portion of mamma.
- Anatomy photo: termscells&tissues/epithelial/exocrinegland/exocrinegland1 - Comparative Organology at University of California, Davis - "Exocrine gland (LM, Low)"
- Overview at uwa.edu.au
- Overview at siumed.edu