Histology of the breast

Question 1

Where is the breast found?

Answer 1

Subcutaneously

Question 2

What makes up the secretory tissue of the breast?

Answer 2

15-25 lobules

Each consist of a compound tubulo-acinar gland which drains via a series of ducts leading to the nipple

Question 3

What is found adjacent to the secretory lobules?

Answer 3

Dense fibrous tissue

Adipose tissue

Question 4

What are the suspensory ligaments of the breast?

Answer 4

Larger areas of connective tissue that extend from dermis of skin to the deep fascia overlying the muscle of the anterior chest wall

Question 5

What is the function of the suspensory ligaments of the breast?

Answer 5

Support breast tissue

Found predominantly in the upper breast tissue

Question 6

What is the basic functional secretory unit of the breast?

Answer 6

Terminal Duct Lobular Unit (TDLU)

Question 7

Where will terminal ductules lead to in a non-lactating breast?

Answer 7

Intralobular collecting duct which leads into the lactiferous duct for that lobe

Question 8

What does the lactiferous duct turn into when it reaches the nipple?

Answer 8

Lactiferous sinus

Question 9

What does the lobule of the breast exhibit?

Answer 9

Extralobular and intralobular ducts
Rudimentary secretory acini
Dense fibrocollagenous connective tissue surrounding lobule
Looser connective tissue surrounding acini within lobule
Adipose tissue between lobules

Question 10

What type of epithelium lines the acini?

Answer 10

Secretory epithelial cells; vary from cuboidal to columnar

Question 11

What surrounds the secretory cells of the acinus in the breast?

Answer 11

Myoepithelial cells (MEp) 
Contractile cells which are surrounded by basal lamina

Question 12

What type of epithelium lines the lactiferous ducts?

Answer 12

Epithelium that varies from thin stratified squamous to stratified cuboidal

Question 13

What type of epithelium covers the nipple

Answer 13

Highly pigmented keratinized stratified squamous epithelium

Question 14

What makes up the core of f the nipple?

Answer 14

Dense irregular connective tissue mixed with bundles of smooth muscle

Question 15

What is interesting about the sebaceous glands of the nipple?

Answer 15

Open directly onto the surface of the nipple

Question 16

How does the breast change in the menstrual cycle?

Answer 16

Luteal phase; epithelial cells increase in height, lumina of duct is enlarged and small amounts of secretions appear in duct

Question 17

How does the breast tissue change in the 1st trim?

Answer 17

Elongation and branching of epithelial cells of glands and myoepithelial cells

Question 18

How does the breast tissue change in 2nd trim?

Answer 18

Glandular tissue continues to develop with differentiation of secretory alveoli 
Plasma cells (IgA) and lymphocytes infiltrate local connective tissue

Question 19

How does the breast tissue change in the 3rd trim?

Answer 19

Secretory alveoli continue to mature with development of extensive RER

Question 20

What is the action of oestrogen and progesterone in the lactating mammary gland?

Answer 20

Stimulate proliferation of secretory tissue and fibro-fatty tissue becomes sparse

Question 21

What is the composition of human milk?

Answer 21

88% water
1.5% protein (lactalbumin and casein) 
7% carbohydrate (lactose) 
3.5% lipid 
Ions
Vitamins
IgA Ab

Question 22

How are fat droplets secreted by the breast?

Answer 22

Secreted surrounded by membrane carrying a small amount of cytoplasm with it
APOCRINE secretion

Question 23

How are the proteins in breast milk secreted by the breast?

Answer 23

Protein made in RER and packaged in golgi apparatus
Secreted via vesicles which merge with apical membrane to release contents into ductal system
MEROCRINE secretion

Question 24

What happens to breast tissue post menopause?

Answer 24

Secretory cells of TDLUs degenerate leaving only ducts

In connective tissue, fewer fibroblasts and reduced collagen and elastic fibres