Breast Histology Flashcards
where is the glandular breast found?
sub-cutaneous
not actually inside the body really
what is the secretory tissue of the breast made up of?
15-25 lobes each consisting of a compound tubulo-acinar gland which drains via a series of ducts leading to the nipple
what are lactiferous ducts?
each duct drains one lobe of the breast to the nipple
branching
other components of the breast?
dense fibrous tissue adjacent to the secretory lobules which in turn i surrounded by adipose tissue
how do lobules change in lactation?
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basic structure of the non-lactating breast?
amongst the fibrous connective tissue are some larger condensations that extend from the dermis of the skin to the deep fascia of the overlying muscle of the anterior chest wall
= suspensory ligaments
where are suspensory ligaments most pronounced and what do they do?
upper breast
support the breast tissue
what is the terminal duct lobular unit (TDLU)?
basic functional secretory unit of the breast
terminal ductules lead into an intralobular collecting duct which leads into the lactiferous duct for that lobe
the lactiferous duct then leads to the nipple passing through an expanded duct region near the nipple termed the lactiferous sinus
where does proliferation occur if breast becomes active?
terminal ductules of acini?
describe the structure of the lobule?
exhibits both extralobular and intralobular ducts and rudimentary secretory acini
surrounded by dense fibrocollagenous connective tissue
loose connective tissue within lobule surrounds the acini (allows rapid expansion in pregnancy)
adipose tissue found between lobules
describe the secretory epithelial cells of the lobule
cuboidal and columnar secretory epithelial cells line the acini
secretory cells are surrounded by myoepithelial cells
function of the myoepithlial cells which surround the secretory cells lining acini?
contractile properties
expel milk etc?
how may larger ducts (e.g lactiferous ducts) differ?
lined by an epithelium that varies from a thin stratified squamous to stratified cuboidal
myoepithelial cells are also present
where are mammary glands proposed to have originated from?
sweat glands
describe the structure of the nipple
wrinkled surface
covered by thin highly pigmented keratinized stratified squamous epithelium
also have sebaceous glands opening directly onto surface
core of dense irregular connective tissue mixed with bundles of smooth muscle
lactiferous ducts pass through
how do the lactiferous ducts change as the travel up the nipple?
as the duct approaches the surface it becomes lined by stratified squamous epithelium and ends directly on surface of skin
deeper, it is lined by stratified cuboidal epithelium
deeper still, lining is only one cell thick
holocrine secretion takes place in the sebaceous glands of the nipple, what is this?
products formed in the cytoplasm
cell membrane then ruptures and products are released, destroying the cell
happens in exocrine glands
how does the breast change in menstrual cycle in the absence of pregnancy?
during the luteal phase the epithelial cells increase in height, the lumina of the ducts become enlarged and small amounts of secretions appear in the ducts
main breast changes in 1st trimester of pregnancy?
elongation and branching of the smaller ducts combined with proliferation of the epithelial cells of the glands and the myoepithelial cells
main breast changes in 2nd trimester?
glandular tissue continues to develop with differentiation of secretory alveoli
plasma cells and lymphocytes infiltrate the nearby connective tissue
main breast changes in 3rd trimester?
secretory alveoli continue to mature with development of extensive rough endoplasmic reticulum
other general changes in pregnancy?
reduction in amount of connective tissue and adipose tissue present
which is the secretory Ig?
IgA
what stimulates the proliferation of secretory tissue and loss of fibro-fatty tissue
oestrogen and progesterone
approximate composition of human milk?
88% water 1.5% protein 7% carbohydrate 3.5% lipid small quantities of ions, vitamins and IgA antibodies
different components of milk are secreted in different ways, how are lipids secreted?
apocrine secretion
droplets are secreted surrounded by membrane and carrying a small amount of cytoplasm with it (basically pinched out of the cell)
how are proteins in milk secreted?
merocrine secretion (most common type of secretion in the body) proteins are made in rER, packaged in the golgi and secreted via vesicles which merge with the apical membrane to release only their contents into the duct system AKA exocytosis
how does the mammary gland change in menopause?
the secretory cells of the TDLUs degenerate leaving only ducts
in the connective tissue, there are fewer fibroblasts and reduced collagen and elastic fibres
