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25 Cards in this Set
- Front
- Back
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What types of glands are mammary glands and what are they derived from?
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-Specialized accessory glands.
-Are really Modified Apocrine Sweat Glands -Are Ectodermally Derived |
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Development - Embryo: Mammary Ridges, Primary Bud, Secondary Buds, Lactiferous Ducts, Supernumary Nipples
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-During the 4th week of development, a pair of epidermal thickenings called Mammary Ridges develop along either side of the body.
-At the site of breast development (and future nipple), the epidermis proliferates into the underlying dermis to form the Primary Bud -By the 12th week, several Secondary Buds have formed, which become canalized to from the Lactiferous Ducts -Sometimes portions of the mammary ridges persist (they normally disappear) and Supernumary Nipples result (Polythelia) |
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Development - Infantile
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The breast consists of rudimentary (lactiferous) ducts surrounded by abundant CT
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Development - Puberty: Ovarian Estrogens and 3 mechanisms, and mammary glands in males
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-In females, breast develop under the influence of Ovarian Estrogens via 3 mechanisms
1) Accumulation of CT 2) Accumulation of adipose tissue 3) Proliferation of ducts deep in the breast to form lobules -In males, since there is minimal estrogen present, the mammary glands retain the infantile structure |
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Breast consists of what types of glands and where do they reside, lobules and ducts, alveoli
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-The breast consists of 15-20 Compound Tubuloalveolar Glands that reside in 15-20 Lobes.
-The lobes contain Lobules that contain clusters of Ducts, which in the Active breast, become Alveoli (secretory units). |
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Intralobular CT vs. Interlobular CT
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The Intralobular CT is slightly less dense and is more cellular than the Interlobular CT, which contains adipose tissue
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Secretory Alveoli - epithelium, cells found here
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-Lined by a single layer of epithelial cells that may be cuboidal or columnar
-Myoepthelial Cells lie between the base of the epithelium and the basement membrane - important part of the milk ejection reflex |
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Intralobular ducts - reside where, function, epithelium, cells found, drain into what
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-Reside Within the Lobules
-Drain the secretory alveoli -Simple cuboidal - these cells also secrete so hard to find in EM -Myoepithelial cells found beneath the epithelium -The intralobular ducts of each lobule drain into the Interlobular Ducts (located in the CT BETWEEN lobules) that are lined with simple cuboidal and have myoepithelial cells present |
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Each lobe is drained by...
Epithelium of what drains it |
-Drained by a Lactiferous Duct which receives contents of the interlobular ducts within the lobe
-Stratified cuboidal/columnnar |
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Each lactiferous duct becomes...
Epithelium of what it becomes |
-Widens at the nipple to become the Lactiferous sinus
-Epithelium becomes stratified squamous at the opening of the nipple |
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Nipple - covered by what type of epithelium, CT around the lactiferous ducts is rich in what 2 things and what are they essential for
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-Covered by keratinized stratified squamous (skin) that is continuous with the pigmented Areola and the surrounding skin.
-The CT around the ducts in the nipple is rich in smooth muscle and sensory nerve endings, which are essential for the Milk Ejection Reflex to occur during nursing |
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Functional Changes in the Adult Mammary Glands: Resting (inactive) Breast - milk secretions and lobules
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-Is not secreting or preparing to secrete milk, so there are few secretory alveoli.
-Lobules contain small clusters of blind-ended ducts embedded in loose CT |
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Functional Changes in the Adult Mammary Glands: Active Breast - hormones (4) and their functions, and changes in epithelium
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-If pregnancy occurs, the hormones Estrogen, Progesterone, Prolactin (from pituitary), and hCS are released.
-Estrogen and Progesterone act on breast tissue and cause intense proliferation of ducts and secretory alveoli. They inhibit the effects of prolactin and hCS prior to birth. -After birth, the effects of hCS allow lactation to begin and the simple columnar epithelium of the alveoli becomes low cuboidal as milk production increases. |
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Active Breast - Lactation: components of milk (4) - protein secretion, lipid secretion
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-Milk contains lipids, proteins, immunoglobins (secretory IgA) and sugars.
-Proteins are formed in the RER, packaged into vesicles by the Golgi and secreted by Exocytosis (Merocrine secretion) into the lumen of the alveolus. -Lipid arises as free floating droplets in cytoplasm, fuse into larger ones are they project into the lumen. THey break free, enveloped by small amount of cytoplasm and a portion of the cell membrane, called an Apocrine Secretion |
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Active Breast - Colostrum - what is it, contains what and what do these components do
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-Colostrum is a very low fat, high protein secretion that is produced right after birth.
-Contains Secretory IgA (immunoglobins) derived from plasma cells present in the CT -These immunoglobins confer Passive Immunity to the suckling infant. |
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Active Breast - Prolactin and Prolactin Inhibitory Factor (PIF)
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-After birth, the placental hormones are no longer secreted and the breast activity is maintained by prolactin.
-The pituitary gland is stimulated to secrete prolactin by the infant suckling -The production of hypothalamic PIF is inhibited by suckling. -PIF inhibits the production and release of prolactin |
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Active Breast - Milk Ejection Reflex, Oxytocin - released from where, what does it do
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-Milk Ejection Reflex occurs when the tactile receptors in the nipple are stimulated by suckling.
-In this relfex, the hormone Oxytocin is released from the Neurohypophysis (neural lobe of pituitary gland) into the bloodstream -Oxytocin rapidly stimulates contraction of myoepithelial cells surrounding secretory alveoli and ducts, resulting in release of milk from nipple |
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Functional Changes in Adult Mammary Glands - Regression of the Mammary Gland - when does it happen and what happens to alveoli
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-Occurs when suckling by the infant ceases (weaning).
-During first few days, alveolar epithelium is flattened due to distension of alveoli w/milk, alveoli gradually collapse, increase in CT and adipose tissue. -Number of intraepithelial macrophages increases, most of alveoli are replaced by the CT and remaining appear as scattered cords of epithelial cells |
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Functional Changes in Adult Mammary Glands - Involution of the Mammary Gland - occurs when, what happens to alveoli and ducts, and to the gland
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-Occurs after menopause b/c of reduction in circulating estrogen
-Epithelium of alveoli and ducts atrophies, reduction in adipose tissue, and gland returns to a prepubertal condition (mostly CT w/few ducts) |
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Clinical Significance - Chronic Cystic Disease
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-the intralobular discs may lose their continuity with the remainder of the duct system and fluid filled cysts of varying sizes are formed
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Clinical Significance - Gynecomastia
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-Most common Male Breast Disorder
-Not a tumor but rather just an increase in the amount of a man's breast tissue. -Common among teenage boys due to changes in hormone balance during adolescence. -Rarely, it can Gynecomastia can occur b/c tumors or diseases of certain endocrine glands cause a man's body to produce more estrogen |
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Clinical Significance - Carcinoma (3 types)
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-The breast is the most common site of cancer in women and carcinomas can arise from the glandular and ductal structures of the breast; most arise from the lactiferous ducts
1) Ductal Carcinoma In Situ (DCIS) 2) Infiltrating (invasive) Ductal Carcinoma (IDC) 3) Infiltrating (invasive) Lobular Carcinoma (ILC) -There are also several less common types of breast cancer. Men can develop breast cancer; the most common is IDC |
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Ductal Carcinoma In Situ (DCIS)
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-This is breast cancer at its earliest stage (0).
-The cancer is confined to the ducts and has not spread through the walls of the ducts into the fatty tissue of the breast. -Best way to find it is w/mammogram, its almost always curable |
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Infiltrating (invasive) Ductal Carcinoma (IDC)
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-This cancer starts in a duct, breaks through the wall of the duct, and invades fatty tissue of the breast
-From there it can spread. -IDC is the most common type of breast cancer - 80% of cases |
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Infiltrating (invasive) Lobular Carcinoma (ILC)
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-This cancer starts in the milk glands (lobules) and then can spread
-Between 10-15% of invasive breast cancers are of this type. |
