Breast Histology

Question 1

where is the glandular breast found?

Answer 1

sub-cutaneous

not actually inside the body really

Question 2

what is the secretory tissue of the breast made up of?

Answer 2

15-25 lobes each consisting of a compound tubulo-acinar gland which drains via a series of ducts leading to the nipple

Question 3

what are lactiferous ducts?

Answer 3

each duct drains one lobe of the breast to the nipple

branching

Question 4

other components of the breast?

Answer 4

dense fibrous tissue adjacent to the secretory lobules which in turn i surrounded by adipose tissue

Question 5

how do lobules change in lactation?

Answer 5

//

Question 6

basic structure of the non-lactating breast?

Answer 6

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

Question 7

where are suspensory ligaments most pronounced and what do they do?

Answer 7

upper breast

support the breast tissue

Question 8

what is the terminal duct lobular unit (TDLU)?

Answer 8

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

Question 9

where does proliferation occur if breast becomes active?

Answer 9

terminal ductules of acini?

Question 10

describe the structure of the lobule?

Answer 10

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

Question 11

describe the secretory epithelial cells of the lobule

Answer 11

cuboidal and columnar secretory epithelial cells line the acini
secretory cells are surrounded by myoepithelial cells

Question 12

function of the myoepithlial cells which surround the secretory cells lining acini?

Answer 12

contractile properties

expel milk etc?

Question 13

how may larger ducts (e.g lactiferous ducts) differ?

Answer 13

lined by an epithelium that varies from a thin stratified squamous to stratified cuboidal
myoepithelial cells are also present

Question 14

where are mammary glands proposed to have originated from?

Answer 14

sweat glands

Question 15

describe the structure of the nipple

Answer 15

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

Question 16

how do the lactiferous ducts change as the travel up the nipple?

Answer 16

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

Question 17

holocrine secretion takes place in the sebaceous glands of the nipple, what is this?

Answer 17

products formed in the cytoplasm
cell membrane then ruptures and products are released, destroying the cell
happens in exocrine glands

Question 18

how does the breast change in menstrual cycle in the absence of pregnancy?

Answer 18

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

Question 19

main breast changes in 1st trimester of pregnancy?

Answer 19

elongation and branching of the smaller ducts combined with proliferation of the epithelial cells of the glands and the myoepithelial cells

Question 20

main breast changes in 2nd trimester?

Answer 20

glandular tissue continues to develop with differentiation of secretory alveoli
plasma cells and lymphocytes infiltrate the nearby connective tissue

Question 21

main breast changes in 3rd trimester?

Answer 21

secretory alveoli continue to mature with development of extensive rough endoplasmic reticulum

Question 22

other general changes in pregnancy?

Answer 22

reduction in amount of connective tissue and adipose tissue present

Question 23

which is the secretory Ig?

Answer 23

IgA

Question 24

what stimulates the proliferation of secretory tissue and loss of fibro-fatty tissue

Answer 24

oestrogen and progesterone

Question 25

approximate composition of human milk?

Answer 25

88% water
1.5% protein
7% carbohydrate
3.5% lipid
small quantities of ions, vitamins and IgA antibodies

Question 26

different components of milk are secreted in different ways, how are lipids secreted?

Answer 26

apocrine secretion
droplets are secreted surrounded by membrane and carrying a small amount of cytoplasm with it (basically pinched out of the cell)

Question 27

how are proteins in milk secreted?

Answer 27

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

Question 28

how does the mammary gland change in menopause?

Answer 28

the secretory cells of the TDLUs degenerate leaving only ducts
in the connective tissue, there are fewer fibroblasts and reduced collagen and elastic fibres