Breast Histology

Question 1

what makes up the structure of the breast

Answer 1

15-25 secretory lobules consisting of a tubulolacinar glands which drain via a series of ducts to the nipple

dense fibrous tissue

adipose tissue

Question 2

what changes occur in the breast during lactation

Answer 2

secretory lobules swell up and take up more space in the breast

Question 3

what does the fibrous connective tissue in the breast form

Answer 3

suspensory ligaments - are packed in between the secretory lobules

suspend the breast from the clavicle or from the fascia under the breast

Question 4

what is the basic functional secretory unit of the breast

Answer 4

the terminal duct lobular unit

in the non lactating breast the TDLU leads to the intralobar collecting duct, which leads to the lactiferous duct for that love

the lactiferous duct drains to the nipple

Question 5

what is within the lobules

Answer 5

secretory epithelial cells which line the lobules and vary from cuboidal to columnar

secretory cells of the lobules are surrounded by myoepithelial cells which are contractile

Question 6

what are the larger ducts lined by

Answer 6

epithelium varying from a thin squamous to stratified cuboidal

myoepithelial cells are also present

Question 7

what covers the outside of the nipple

Answer 7

thin, highly pigmented keratinised stratified squamous epithelium

also have sebaceous glands which open onto the surface (not into hair follicles like the rest of the body)

Question 8

how do the sebaceous glands secrete sebum directly onto the nipple (without a hair follicle)

Answer 8

holocrine secretion

Question 9

what changes happen to the breast in the luteal phase of the menstrual cycle

Answer 9

epithelial cells increase in height

lumina of ducts become enlarged

small amounts of secretion appear in ducts

Question 10

what breast changes occur in pregnancy (T1)

Answer 10

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

Question 11

what breast changes occur in pregnancy (T2)

Answer 11

glandular tissue continues to develop with differentiation of secretory alveoli

plasma cells and lymphocytes infiltrate the nearby connective tissue

Question 12

what changes occur in pregnancy (T3)

Answer 12

secretory alveoli continue to mature with development of extensive rER??

Question 13

what is the composition of human milk

Answer 13

88% water
1.5% protein
7% carbohydrate
3.5% lipid

with small quantities of ions, vitamins and IgA antibodies

Question 14

how are different components of milk secreted from the secretory ducts

Answer 14

via different mechanisms

Apocrine secretion
-lipid droplets secreted surrounded by a membrane with small amounts of cytoplasm

(yellow in picture)

Merocrine secretion

• only thing released is the product
• product is packaged in the Golgi apparatus
• merge the apical membrane to form vesicles which release the content into the duct system

(purple in picture)

Question 15

what breast changes occur in menopause

Answer 15

terminal ductal lobar units degenerated leaving only the ducts

there are fewer fibroblasts and reduced collagen and elastic fibres

Question 16

what phrase is used to describe breast structure

Answer 16

tubulo-acinar

Question 17

what is the pathway for milk excretion from production to the nipple

Answer 17

terminal ductal 
intralobular collecting duct 
extra lobular collecting duct 
lactiferous duct 
lactiferous sinus 
nipple

Question 18

what type of cell lines the outside of the nipple

Answer 18

stratified squamous epithelium