Dorlands
/Elsevier d_29/12314912 FMA 58006 | TA A16.0.02.010 | |
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Latin ductus lactiferi, tubulus lactiferi | ||
Lactiferous ducts form a tree branched system connecting the lobules of the mammary gland to the tip of the nipple. They are also referred to as galactophores, galactophorous ducts, mammary ducts, mamillary ducts and milk ducts. They are the structures which carry milk toward the nipple in a lactating female.
Contents
Structure
Lactiferous ducts are lined by a columnar epithelium supported by myoepithelial cells. When a woman is not lactating, the lactiferous duct is frequently blocked by a keratin plug. This plug prevents bacteria from entering the duct in non-lactating women. Prior to 2005, it was thought within the areola the lactiferous duct would dilate to form the lactiferous sinus in which milk supposedly accumulates between breastfeeding sessions. However new research suggests that lactiferous sinus does not exist.
Function
The columnar epithelium plays a key role in balancing milk production, milk stasis and resorption. The cells of the columnar epithelium form tight junctions which are regulated by hormones and local factors like pressure and casein content. Prolactin and/or placental lactogen are required for tight junction closure while progesterone is the main hormone preventing closure before birth.
Clinical significance
The majority of breast diseases either originate from lactiferous ducts or are closely related. The high susceptibility to benign and malignant diseases is in part a consequence of the cycling hormonal growth stimulation resulting in a high cell turnover and accumulation of defects and complicated hormonal equilibrium which is highly sensible to disturbance.