Mammary Glands

Question 1

immature breast structure

Answer 1

pigmented nipple and areola

lactiferous ducts

same in both sexes

Question 2

puberty breasts structure

Answer 2

nipples and areola enlarge, proliferation of duct system, increase in stroma (collangeous CT and fat) due to estradiol

Note: estrogen is mostly mitogen which causes proliferation

Question 3

structure of adult breasts

Answer 3

15-20 lobes (alveolar lobules are organized within each lobe) of branched tubuloalveolar glands

lobule = functional unit mammary gland

each lobule/lobe narrows down to lactiferous ducts and sinuses which open up to surface at areola

ducts dilate to form lactiferous sinuses for milk storage

stroma = lots of adipose and collagenous CT

Question 4

resting/inactive mammary gland

Answer 4

no glandular tissue

nipples and areola = pigmented, keratinized, stratified squamous epithelium

areola = has numerous sweat and sebaceous glands

dermis = dense, irregular CT with SmM and elastic fibers

nipples are richly innervated

Question 5

epithelium of ductal system –> lactiferous duct

Answer 5

stratified squamous mucosal (not on surface yet but close to surface) and

stratified cuboidal/columnar (unique)

Question 6

terminal lobular duct epithelium

Answer 6

line a tube

simple columnar/cuboidal epithelium

supplies lobules (made from branching ductal epithelium with no alveolar development –> buds of alveoli , but no differentiation to produce milk products)

buds will rapidly proliferate and differentiate at pregnancy under control of estrogen

Question 7

myoepithelial cells of mammary gland

Answer 7

have contractile properties to squeeze alveoli and ducts to force milk products out under control of

oxytocin

Question 8

stroma within breast tissue

Answer 8

interlobar and interlobular = dense, irregular CT and adipose tissue

within lobule (intralobular) = loose CT with plasma cells, WBCs, eosinophils

Question 9

breast carcinoma

Answer 9

cells start unchecked proliferation –> get multilayer epithelial cells within duct

Question 10

ductal carcinoma situ

Answer 10

if the cancer stays within the duct

better prognosis than if it escapes through the basement membrane out into surrounding tissue

Question 11

terminal ductal carcinoma

Answer 11

lobular carcinoma

worse prognosis than ductal carcinoma

Question 12

epithelial cancer cells in breast

Answer 12

can outgrow blood and nutrient supply and begin to die off

will show up as calcifications for radiologists on mammograms

Question 13

hormonal therapy for breast cancer

general

Answer 13

block estrogen dependent proliferation of breast cancer cells

Question 14

structure of adult breast

resting (menstrual cycle changes)

Answer 14

slight proliferation of ducts due to estrogen

slight development of secretory units due to progesterone

histologically no difference

Question 15

structure of adult breast during pregnancy (active mammary gland)

Answer 15

astronomical levels of estradiol and progesterone during pregnancy

hCG = produced by the placenta

progesterone –> starts from corpus luteum and then placenta takes over

prolactin = majority is maternal

1st half of preg = proliferative (secretory alveoli develop)

2nd half = lobules enlarge from hypertrophy of alveoli and secretion of colostrum
–> get proliferation and hypertrophy of alveoli

Question 16

glandular tissue in breast only present during…

Answer 16

= alveolar development

only present during pregnancy and lactation

Question 17

massive amounts of proliferation of what epithelium during pregnancy?

Answer 17

alveolar and ductal epithelium

due to estrogen

differentiation of alveolar epithelium –> to produce milk (under control of progestin)

marked reduction in CT (stroma)

Question 18

ductal system during pregnancy

Answer 18

completes development

secretory alveolar cells = cuboidal (produce milk)

ductal epithelial cells = columnar (conduct milk)

Question 19

what happens breast tissue during lactation

Answer 19

glandular tissue secretory unti = alveoli

alveoli dilated with secretory products

cuboidal epithelium is compressed

thin CT septae

all proliferation is complete

proteins secreted on apical surface into lumen and transported into ducts out of breast

majority of secretory products accumulate during lactation

Question 20

secretory products during lactation

Answer 20

colostrum (days 1-3), protein rich, vitamin A rich, IgA

milk (begins day 4) = protein (1.5%), fat (4%), lactose (7%) and IgA

Question 21

prolactin

Answer 21

secretion is suppressed by dopamine in non pregnant women and suppressed during pregnancy (to a lesser extent) by very high levels of estrogen and progesterone

stimulates pubertal development of breast tissues and further hyperplasia during pregnancy

stimulates milk synthesis and secretion after drop in estrogen and progesteron at end of pregnancy

Question 22

parathyroid hormone

Answer 22

activates Ca2+ mobilization in bone (inhibited by estradiol) and promotes activation of vitamin D

lactating breast produces PTHrP (PTH related peptide) that moves vitamin D precursor from inactive to active form

–> goest to intestine and leads to Ca2+ binding proteins for Ca2+ absorption –>

Ca2+ to bone to activate osteoblasts/osteoclasts to mobilize Ca2+ –>

induces osteocalcin to bind Ca2_ to collagen –>

free Ca2+ = important for producing milk for lactation

Question 23

oxytocin

Answer 23

(from posterior pituitary)

causes contraction of myoepithelial cells to move milk through ducts

Question 24

lactogenesis

Answer 24

neuroendocrine relfex of mammary gland

prolactin regulated

suckling sends nerve impulse to brain –> release prolactin and oxytocin –>

causes alveoli to secrete milk (prolactin) and

myoepithelial cells to squeeze milk towards surface (oxytocin)

Question 25

oxytocin regulates let down of what

Answer 25

milk

Question 26

lactational amenorrhea

Answer 26

high levels of prolactin will inhibit secretion of GnRH that results in amenorrhea

Question 27

regression after cessatino of lactation

Answer 27

resorption of glandular tissue

reestablishment of CT and adipose tissue

massive rounds of apoptosis

Question 28

postmenopausal involuation and dying off of excess tissue

Answer 28

ovaries shut down (lose estrogens and progesterone levels)

CT decreases in amount and density increases (less cellular and more fibrous)

further involution of ducts and secretory untis

Question 29

prolactin deficiency

Answer 29

caused by destruction of anterior pituitary and results inability to lactate

Question 30

prolactin excess

Answer 30

can cause infertility and complete loss of menses