Lactiferous ducts !
The lactiferous ducts are the milk ducts that carry milk from each lobe to the nipple; most breast cancers start in their lining.
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What it is
15 to 20 ducts, one per lobe, that carry milk to the nipple; each widens into a small lactiferous sinus just under the areola.
What it does
Drain milk from the lobules to the openings on the nipple during breastfeeding.
Key facts
- Where
- One main duct per lobe converging radially on the nipple, each widening behind it into a lactiferous sinus
- Function
- Carry milk; myoepithelial cells contract with oxytocin (let-down); most breast carcinomas arise from the duct epithelium
Relations
- Course
- From the terminal ductules of each lobule, branches join into one duct per lobe that runs radially toward the nipple, widens into a lactiferous sinus under the areola and narrows again to open on the nipple
- Superficial
- The areola and the nipple, over their last segment and the lactiferous sinuses
- Contents
- Milk during lactation; at other times a little secretion and shed cells
How to find it
Their openings are the small pores on the tip of the nipple. A duct that discharges is identified by gentle pressure around the areola, then cannulated through its pore for ductography or followed back from it in a microdochectomy.
On imaging
Ultrasound shows dilated retroareolar ducts and intraductal masses. Mammography finds ductal carcinoma in situ mostly as fine, branching or linear calcifications along a duct. Ductography outlines the discharging duct when ultrasound is unclear.
Common problems
- Ductal carcinoma in situ (DCIS) and invasive ductal carcinoma: the most common breast cancers start in the lining of the ducts.
- Intraductal papilloma: a benign growth, the usual cause of bloody discharge from a single duct.
- Mastitis and breast abscess, mostly while breastfeeding.
How it is diagnosed
Mammography (DCIS often shows as fine calcifications), ultrasound, a study of any nipple discharge, and biopsy.
Treatment
- Mastitis: keep emptying the breast, antibiotics; an abscess is drained.
- DCIS and ductal cancer: surgery (lumpectomy or mastectomy) with radiotherapy and other treatment as needed.
Clinical notes
- Duct ectasia: widened subareolar ducts, mostly around menopause, with thick, sticky, multicoloured discharge and sometimes a slit-like nipple retraction
- Lactational mastitis follows milk stasis and bacteria entering through cracked nipples; a breast abscess is a walled-off collection, usually drained by needle aspiration under ultrasound
- Microdochectomy removes one duct for single-duct discharge; total duct excision removes all major ducts behind the nipple
- Ductal carcinoma in situ stays inside the duct, often following one segment of the breast from the nipple outward
Anatomical variants
- The number of ducts varies: classic texts give 15–20 openings on the nipple, while ultrasound and dissection studies often count fewer
Development
In the embryo 15–20 solid cords grow from the mammary bud into the underlying tissue and later hollow out to become the lactiferous ducts, which open onto the future nipple.
Related conditions
- Hereditary breast and ovarian cancer syndrome (BRCA1/BRCA2)
- Intraductal papilloma of the breast
- Breast cancer
- Acute mastitis
- Breast abscess
- Fibrocystic breast changes
Test yourself
Think of the answer, then tap the question to see it.
What is the commonest cause of bloody discharge from a single lactiferous duct?
Intraductal papilloma, usually in a duct just behind the nipple.
What marks a ductal carcinoma as invasive?
Breaking through the outer myoepithelial layer and the basement membrane of the duct; ductal carcinoma in situ stays inside the duct.
How does ductal carcinoma in situ typically show on mammography?
As fine, branching or linear calcifications along a duct.
What is duct ectasia?
Widened subareolar ducts, mostly around menopause, with thick, sticky, multicoloured discharge and sometimes slit-like nipple retraction.
Educational information, not medical advice. For any symptom, see a health professional.
Its names
- Official Latin (TA2)
- ductus lactiferi; sinus lactiferi TA2 7103
- Official Spanish (DeCS)
- Conductos lactíferos
- English (TA2)
- Lactiferous ducts
Sources: Terminologia Anatomica (TA2); Anatomy, Thorax, Breast; Anatomy, Thorax: Mammary Gland; 27.2 Anatomy and Physiology of the Ovarian Reproductive System (OpenStax (Rice University), 2022) · adapted, CC BY 4.0.
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Representative model, for educational purposes only.