The Anatomy and Histology

of the

Normal Human Breast

images and text by

Dr. Hanne Jensen

University of California, Davis

Department of Pathology School of Medicine.

Click on the image for the full image.

slide1.jpg
591.49 Kb
Slide 1. The milk line develops in the fetus extending from the axilla to the grain as an epidemically derived structure from the skin. The slide shows a transverse section with early branching of the major lactiferous ducts. Epon imbedded toluidine blue staining. 63X

slide2.jpg
404.42 Kb
Slide 2. In females a doughnut shaped disk of stroma, into which the branching duct tree descends, is forming several years before the onset of menses. This 2mm thick slice of breast shows the blue staining of the epithelium since nuclei stain with the hematoxylin. Note the early formation of lobules around one of the ducts and the convergence of the major lactiferous ducts at the nipple. 1X

slide3.jpg
483.71 Kb
Slide 3. As the breast enlarges the dense connective tissue stroma is dispersed by fat. The c denotes the area magnified 5X in the next slide.

slide4.jpg
438.48 Kb
Slide 4. The blue balls are the cellular lobules, the potentially milk microorgans. They stain blue since hematoxylin stains the nuclei. 3X

slide5.jpg
86.07 Kb
Slide 5. Each breast is composed of 6-8 LOBES shaped like pie pieces around the nipple. Contrast material was injected into one major lactiferous duct and an x-ray was taken and illustrates the branching duct tree of a single lobe. 1X

slide6.jpg
516.22 Kb
Slide 6. The major lactiferous ducts converge on the nipple in the slice. 2X

slide7.jpg
595.41 Kb
Slide 7. This transverse cut shows some of the 5 lactiferous ducts filled with secretions. 1.5X

slide8.jpg
502.20 Kb
Slide 8. Two major lactiferous ducts are seen longitudinally to descend several centimeters before any blue lobules are formed. This is indeed nature's nursing bottle. The area needs to be empty so that the infant can bite down on the lactiferous ducts while nursing. 1X

slide9.jpg
582.88 Kb
Slide 9. This histological section shows the nipple and some areola. Epithelium stains blue with hematoxylin and stroma stains red with eosin. Note lactiferous duct at the surface of the nipple. It is plugged with keratin. 1X

slide10.jpg
1194.33 Kb
Slide 10. At higher magnification the keratin plug is seen better. This mechanical barrier prevents bacteria from entering the duct in non-lactating women. 63X

slide11.jpg
591.75 Kb
Slide 11. The histologic slide of a major duct is seen in 2 dimensions. 6.3X

slide12.jpg
542.79 Kb
Slide 12. The same duct is seen in 3 dimensions in the breast slice. 6.3X

slide14.jpg
578.48 Kb
Slide14. A cluster of TDLU is seen at higher magnification from the previous slide. Note how the TDLU radiate around the small duct like spokes of a wheel. That architecture will allow the TDLU to expand in all directions during physiological hyperplasia of pregnancy and lactation. 3.5X

slide15.jpg
412.41 Kb
Slide 15. This diagram shows the branching ducts (D). The extralobuler terminal duct (ETD). From the intralobular part of the terminal duct (ITD) ductules (DTL) develop like test tubes as blindly ending structures. 30-50 ductules are present in each TDLU and can be alikened to the delicate petals of a daisy.

slide16.jpg
880.57 Kb
Slide 16. The histologic appearance of several TDLU at low magnification. 10X
slide17.jpg
732.77 Kb
Slide 17. At higher magnification note the sharp interphase between dense extralobuler connective tissue and each TDLU. 25X
slide18.jpg
733.77 Kb
Slide 18. At even higher magnification the loose intralobular stroma is noted investing the ductules. 63X
slide19.jpg
516.54 Kb
Slide 19. A single ductule cut transversely shows two cell types, an inner layer of secretory cells with abundant mitochondria and an outer sparse cell layer of myoepithelium with sparse cytoplasm. Epon imbedded toluidine blue stained. 250X slide20.jpg
392.19 Kb
Slide 20. A single ductule is shown in this electronmicrograph. Fat droplets are noted in the apical cytoplasm of the secretory cells adjoining the lumen. The outer flattened myoepithelium contains abundant cytoplasmic filaments. The myoepithelium contracts when oxytoxin is released from the posterior pituitary gland during the early phase of nursing. Thus, the milk in the lobules is literally squeezed into the duct tree during nursing. This pituitary hormone is called the let down factor. Prolactin and endorphins are released into the blood stream from the pituitary by the let down factor stimulation. The nursing mother is thus experiencing extreme well being and contentment from her surge of endorphin hormone, the happiness hormone you could call it. The prolactin ensures nurturing behavior of the offspring and is the love hormone Nature has devised a pay-off in all facets of reproductive behavior. 4000X

slide21.jpg
663.12 Kb
Slide 21. Each ductule is invested with a basement membrane stained red with Periodic Acid Schiff (PAS). 100X

slide22.jpg
513.52 Kb
Slide 22. Pregnancy hormones induce hyperplasia of TDLU. In this slide from a 5 months pregnancy the enlarged lobules have crowded out the extralobular connective tissue. 5X
slide23.jpg
651.05 Kb
Slide 23. This histologic slide shows the glandular hyperplasia crowding out the intralobular stroma. 200X
slide24.jpg
763.33 Kb
Slide 24. This "Normal" lobule is from a non-pregnant 49 year old female with breast cancer. It has the appearance of a younger female. However, women with breast cancer retain a youthful breast parenchyma.
slide25.jpg
693.52 Kb
Slide 25. This normal lobule is from a 43 year old female with no breast cancer. Note the thickened basement membranes around the ductules. The lobule is starting to become sclerotic. 63X

slide26.jpg
742.88 Kb
Slide 26. This normal lobule displays fewer ductules and denser intralobular stroma. Non-cancerous breast from an 83 year old female. 63X
slide27.jpg
387.49 Kb
Slide 27. In this breast slice the lobules show moderate atrophy. Note the distended duct tree. From a 59 year old female with no breast cancer. 8X

slide28.jpg
464.91 Kb
Slide 28. This breast slice shows complete atrophy of the TDLU but the branching duct tree will remain forever. From a 52 year old female with no breast cancer. 1X

slide29.jpg
371.63 Kb
Slide 29. This breast slice shows the branching duct tree distended with secretion and a few remnants of lobules. The flowing tree of the young breast has become cacti in the desert. 4X

slide30.jpg
493.95 Kb
Slide 30. This breast slice illustrates the branching duct tree and a single TDLU with a delicate terminal duct. The microarchitecture of TDLU is recapitulated in pre-cancerous lesions and ductal carcinoma in-situ, as you will see later.

slide31.jpg
544.76 Kb
Slide 31. In this slice at 10X the punctate appearance of the lobule is due to the individual ductules making it possible to discern it as a normal lobule. 10X

slide32.jpg
458.29 Kb
Slide 32. This slice of breast has been stained supravitally with methylene blue chloride. They have the same punctuate appearance so the structures are normal lobules. 6X

slide33.jpg
304.25 Kb
Slide 33. Two such lobules have been dissected for experiments. They are alive. 6X

Page 1 of 1

November 22, 1999

slide1.jpg 591.49 Kb Slide 1. The milk line develops in the fetus extending from the axilla to the grain as an epidemically derived structure from the skin. The slide shows a transverse section with early branching of the major lactiferous ducts. Epon imbedded toluidine blue staining. 63X	slide2.jpg 404.42 Kb Slide 2. In females a doughnut shaped disk of stroma, into which the branching duct tree descends, is forming several years before the onset of menses. This 2mm thick slice of breast shows the blue staining of the epithelium since nuclei stain with the hematoxylin. Note the early formation of lobules around one of the ducts and the convergence of the major lactiferous ducts at the nipple. 1X	slide3.jpg 483.71 Kb Slide 3. As the breast enlarges the dense connective tissue stroma is dispersed by fat. The c denotes the area magnified 5X in the next slide.	slide4.jpg 438.48 Kb Slide 4. The blue balls are the cellular lobules, the potentially milk microorgans. They stain blue since hematoxylin stains the nuclei. 3X	slide5.jpg 86.07 Kb Slide 5. Each breast is composed of 6-8 LOBES shaped like pie pieces around the nipple. Contrast material was injected into one major lactiferous duct and an x-ray was taken and illustrates the branching duct tree of a single lobe. 1X
slide6.jpg 516.22 Kb Slide 6. The major lactiferous ducts converge on the nipple in the slice. 2X	slide7.jpg 595.41 Kb Slide 7. This transverse cut shows some of the 5 lactiferous ducts filled with secretions. 1.5X	slide8.jpg 502.20 Kb Slide 8. Two major lactiferous ducts are seen longitudinally to descend several centimeters before any blue lobules are formed. This is indeed nature's nursing bottle. The area needs to be empty so that the infant can bite down on the lactiferous ducts while nursing. 1X	slide9.jpg 582.88 Kb Slide 9. This histological section shows the nipple and some areola. Epithelium stains blue with hematoxylin and stroma stains red with eosin. Note lactiferous duct at the surface of the nipple. It is plugged with keratin. 1X	slide10.jpg 1194.33 Kb Slide 10. At higher magnification the keratin plug is seen better. This mechanical barrier prevents bacteria from entering the duct in non-lactating women. 63X
slide11.jpg 591.75 Kb Slide 11. The histologic slide of a major duct is seen in 2 dimensions. 6.3X	slide12.jpg 542.79 Kb Slide 12. The same duct is seen in 3 dimensions in the breast slice. 6.3X		slide14.jpg 578.48 Kb Slide14. A cluster of TDLU is seen at higher magnification from the previous slide. Note how the TDLU radiate around the small duct like spokes of a wheel. That architecture will allow the TDLU to expand in all directions during physiological hyperplasia of pregnancy and lactation. 3.5X	slide15.jpg 412.41 Kb Slide 15. This diagram shows the branching ducts (D). The extralobuler terminal duct (ETD). From the intralobular part of the terminal duct (ITD) ductules (DTL) develop like test tubes as blindly ending structures. 30-50 ductules are present in each TDLU and can be alikened to the delicate petals of a daisy.
slide16.jpg 880.57 Kb Slide 16. The histologic appearance of several TDLU at low magnification. 10X	slide17.jpg 732.77 Kb Slide 17. At higher magnification note the sharp interphase between dense extralobuler connective tissue and each TDLU. 25X	slide18.jpg 733.77 Kb Slide 18. At even higher magnification the loose intralobular stroma is noted investing the ductules. 63X	slide19.jpg 516.54 Kb Slide 19. A single ductule cut transversely shows two cell types, an inner layer of secretory cells with abundant mitochondria and an outer sparse cell layer of myoepithelium with sparse cytoplasm. Epon imbedded toluidine blue stained. 250X	slide20.jpg 392.19 Kb Slide 20. A single ductule is shown in this electronmicrograph. Fat droplets are noted in the apical cytoplasm of the secretory cells adjoining the lumen. The outer flattened myoepithelium contains abundant cytoplasmic filaments. The myoepithelium contracts when oxytoxin is released from the posterior pituitary gland during the early phase of nursing. Thus, the milk in the lobules is literally squeezed into the duct tree during nursing. This pituitary hormone is called the let down factor. Prolactin and endorphins are released into the blood stream from the pituitary by the let down factor stimulation. The nursing mother is thus experiencing extreme well being and contentment from her surge of endorphin hormone, the happiness hormone you could call it. The prolactin ensures nurturing behavior of the offspring and is the love hormone Nature has devised a pay-off in all facets of reproductive behavior. 4000X
slide21.jpg 663.12 Kb Slide 21. Each ductule is invested with a basement membrane stained red with Periodic Acid Schiff (PAS). 100X	slide22.jpg 513.52 Kb Slide 22. Pregnancy hormones induce hyperplasia of TDLU. In this slide from a 5 months pregnancy the enlarged lobules have crowded out the extralobular connective tissue. 5X	slide23.jpg 651.05 Kb Slide 23. This histologic slide shows the glandular hyperplasia crowding out the intralobular stroma. 200X	slide24.jpg 763.33 Kb Slide 24. This "Normal" lobule is from a non-pregnant 49 year old female with breast cancer. It has the appearance of a younger female. However, women with breast cancer retain a youthful breast parenchyma.	slide25.jpg 693.52 Kb Slide 25. This normal lobule is from a 43 year old female with no breast cancer. Note the thickened basement membranes around the ductules. The lobule is starting to become sclerotic. 63X
slide26.jpg 742.88 Kb Slide 26. This normal lobule displays fewer ductules and denser intralobular stroma. Non-cancerous breast from an 83 year old female. 63X	slide27.jpg 387.49 Kb Slide 27. In this breast slice the lobules show moderate atrophy. Note the distended duct tree. From a 59 year old female with no breast cancer. 8X	slide28.jpg 464.91 Kb Slide 28. This breast slice shows complete atrophy of the TDLU but the branching duct tree will remain forever. From a 52 year old female with no breast cancer. 1X	slide29.jpg 371.63 Kb Slide 29. This breast slice shows the branching duct tree distended with secretion and a few remnants of lobules. The flowing tree of the young breast has become cacti in the desert. 4X	slide30.jpg 493.95 Kb Slide 30. This breast slice illustrates the branching duct tree and a single TDLU with a delicate terminal duct. The microarchitecture of TDLU is recapitulated in pre-cancerous lesions and ductal carcinoma in-situ, as you will see later.
slide31.jpg 544.76 Kb Slide 31. In this slice at 10X the punctate appearance of the lobule is due to the individual ductules making it possible to discern it as a normal lobule. 10X	slide32.jpg 458.29 Kb Slide 32. This slice of breast has been stained supravitally with methylene blue chloride. They have the same punctuate appearance so the structures are normal lobules. 6X	slide33.jpg 304.25 Kb Slide 33. Two such lobules have been dissected for experiments. They are alive. 6X