ANATOMY OF THE NORMAL LOBULE

The lobule is the functional end organ of the mammary gland. It is the source of milk and, unfortunately, breast cancer.

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Slide 25. The lobules are clustered around the branching duct tree and each one is drained via a TERMINAL DUCT . A terminal duct and its lobule is called THE TERMINAL DUCT LOBULAR UNIT (TDLU) because this is the entity that changes in benign, pre-cancerous and cancerous breast disease. Photographed at 3x magnification.
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Slide 26. A cluster of TDLU is seen at higher magnification from the previous slide. Note how the TDLU radiate around the SMALL DUCT (D) like spokes of a wheel. That architecture will allow the TDLU to expand in all directions during physiological hyperplasia of pregnancy and lactation. Arrows point to two terminal ducts, each drains a lobule. Photographed at 8x magnification.
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Slide 27. This diagram shows the branching ducts (D) and the EXTRALOBULAR TERMINAL DUCTS (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 lobule (L) and can be likened to the delicate petals of a daisy. Note that the lobules have varying degrees of development that has been classified by Drs. Russo as LOBULE TYPE 1 - 3.

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Slide 28. The histologic appearance of 3 TDLU are delineated by a black line. They have septa of dense stroma. Photographed at 10x magnification.
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Slide 29. At higher magnification note the sharp interface (arrows) between dense EXTRALOBULAR STROMA and each TDLU. Photographed at 25x magnification.
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Slide 30. At even higher magnification the loose INTRALOBULAR STROMA is noted investing the ductules. Photographed at 63x magnification.

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Slide 31. 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 to which arrows point. Epon imbedded Toluidine Blue stained. Photographed at 250x magnification.
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Slide 32. A single ductule is shown in this electronmicrograph. Fat droplets are noted in the apical cytoplasm of the secretory cells adjoining the lumen (L). Arrows point to the nuclei of the outer flattened myoepithelium that 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 also 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 toward the offspring and is the love hormone. Nature has devised a pay-off in all facets of reproductive behavior. Photographed at 4000x magnification.
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Slide 33. Each ductule is invested with a BASEMENT MEMBRANE stained intensely red with Periodic Acid Schiff (PAS). Photographed at 100x magnification.

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slide25.jpg 374.16 Kb Slide 25. The lobules are clustered around the branching duct tree and each one is drained via a TERMINAL DUCT . A terminal duct and its lobule is called THE TERMINAL DUCT LOBULAR UNIT (TDLU) because this is the entity that changes in benign, pre-cancerous and cancerous breast disease. Photographed at 3x magnification.	slide26.jpg 585.91 Kb Slide 26. A cluster of TDLU is seen at higher magnification from the previous slide. Note how the TDLU radiate around the SMALL DUCT (D) like spokes of a wheel. That architecture will allow the TDLU to expand in all directions during physiological hyperplasia of pregnancy and lactation. Arrows point to two terminal ducts, each drains a lobule. Photographed at 8x magnification.	slide27.jpg 412.41 Kb Slide 27. This diagram shows the branching ducts (D) and the EXTRALOBULAR TERMINAL DUCTS (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 lobule (L) and can be likened to the delicate petals of a daisy. Note that the lobules have varying degrees of development that has been classified by Drs. Russo as LOBULE TYPE 1 - 3.
slide28.jpg 925.23 Kb Slide 28. The histologic appearance of 3 TDLU are delineated by a black line. They have septa of dense stroma. Photographed at 10x magnification.	slide29.jpg 737.17 Kb Slide 29. At higher magnification note the sharp interface (arrows) between dense EXTRALOBULAR STROMA and each TDLU. Photographed at 25x magnification.	slide30.jpg 732.63 Kb Slide 30. At even higher magnification the loose INTRALOBULAR STROMA is noted investing the ductules. Photographed at 63x magnification.
slide31.jpg 520.91 Kb Slide 31. 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 to which arrows point. Epon imbedded Toluidine Blue stained. Photographed at 250x magnification.	slide32.jpg 411.31 Kb Slide 32. A single ductule is shown in this electronmicrograph. Fat droplets are noted in the apical cytoplasm of the secretory cells adjoining the lumen (L). Arrows point to the nuclei of the outer flattened myoepithelium that 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 also 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 toward the offspring and is the love hormone. Nature has devised a pay-off in all facets of reproductive behavior. Photographed at 4000x magnification.	slide33.jpg 670.01 Kb Slide 33. Each ductule is invested with a BASEMENT MEMBRANE stained intensely red with Periodic Acid Schiff (PAS). Photographed at 100x magnification.