Breast Histology

Question 1

What is the breast?

Answer 1

A subcutaneous gland

Question 2

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

Answer 2

15-25 lobes

Question 3

What do breast lobes consist of?

Answer 3

A compound tubule-acinar gland which drains via a series of ducts leading to the nipple

Question 4

What is found adjacent to secretory lobules in the breast? Then what is this surrounded by?

Answer 4

Dense fibrous tissue

Adipose tissue

Question 5

What is found amongst fibrous CT in the breast?

Answer 5

Some larger condensations that extend from the dermis of the skin to the deep fascia overlying the muscle of the anterior chest wall

Question 6

‘Some larger condensations that extend from the dermis of the skin to the deep fascia overlying the muscle of the anterior chest wall’ … what are these called?

Answer 6

Suspensory ligaments

Question 7

Where in the breast do you find most suspensory ligaments?

Answer 7

In the upper breast.

Question 8

What do suspensory ligaments in the upper breast do?

Answer 8

Support the breast tissue

Question 9

What is the basic functional secretory unit of the breast?

Answer 9

The Terminal Duct Lobular Unit (TDLU)

Question 10

In the non-lactating breast, what do terminal ductules lead into?

Answer 10

An intralobular connecting duct

Question 11

What do interlobular connecting ducts lead into?

Answer 11

The lactiferous duct for that lobe

Question 12

What does the lactiferous duct for that lobe lead into?

Answer 12

The nipple, passing through an expanded duct region near the nipple, termed the lactiferous sinus

Question 13

Within the lobule, what line the acini?

Answer 13

Secretory epithelial cells

Question 14

What do secretory epithelial cells vary from?

Answer 14

Cuboidal to columnar

Question 15

What are the secretory cells of the acinus surrounded by?

Answer 15

Myoepithelial cells (MEp).
(appear pink in pic)

Question 16

What are myoepithelial cells?

Answer 16

Contractile epithelial cells

Question 17

What are myoepithelial cells surrounded by?

Answer 17

The basal lamina

Question 18

What are larger ducts – such as a lactiferous duct – lined by?

Answer 18

An epithelium that varies from thin stratified squamous to stratified cuboidal.

Question 19

What is the surface of the nipple like?

Answer 19

Wrinkled

Question 20

What is the surface of the nipple covered by?

Answer 20

A thin, highly pigmented keratinized stratified squamous epithelium.

Question 21

What does the nipple covering have a core of?

Answer 21

Dense irregular connective tissue, mixed with bundles of smooth muscle

Question 22

Describe what type of epithelium lactiferous ducts are lined by.

Answer 22

• Near the surface – stratified squamous epithelium.
• Deeper – stratified cuboidal epithelium.
• Deeper still – duct lining may become only one cell thick.

Question 23

What are also present on the skin of the breast?

Answer 23

Sebaceous glands

Question 24

During the menstrual cycle, changes occur in the breast even in the absence of pregnancy. Describe these.

Answer 24

During the luteal phase, the epithelial cells increase in height, the lumina of the ducts becomes enlarged and small amounts of secretions appear in the ducts.

Question 25

If pregnancy occurs, dramatic changes take place in the breast:

What happens in the 1st trimester?

Answer 25

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

Question 26

If pregnancy occurs, dramatic changes take place in the breast:

What happens in the 2nd trimester?

Answer 26

Glandular tissue continues to develop, with differentiation of secretory alveoli.
Also, plasma cells and lymphocytes infiltrate the nearby connective tissue

Question 27

If pregnancy occurs, dramatic changes take place in the breast:

What happens in the 3rd trimester?

Answer 27

Secretory alveoli continue to mature, with the development of extensive rER.

Question 28

What are all the changes in the breast during pregnancy accompanied by?

Answer 28

A reduction in the amount of connective tissue and adipose tissue present

Question 29

During pregnancy, what do oestrogen and progesterone stimulate (in relation to the breast)?

Answer 29

Proliferation of secretory tissue

Question 30

During pregnancy, what becomes sparse in the breast?

Answer 30

Fibro-fatty tissue

Question 31

Outline the approximate composition of human milk.

Answer 31

• 88% water
• 1.5% protein (mainly lactalbumin and casein)
• 7% carbohydrate (mainly lactose)
• 3.5% lipid

With small quantities of: ions, vitamins and IgA antibodies

Question 32

Explain how lipid droplets are secreted in breastmilk.

Answer 32

Secreted surrounded by a membrane, carrying a small amount of cytoplasm with it (budding)

Question 33

Secreted surrounded by a membrane, carrying a small amount of cytoplasm with it (budding). What is this form of secretion known as?

Answer 33

APOCRINE secretion

Question 34

What are the proteins in milk made in? Describe what then happens to them, including how they are secreted.

Answer 34

• Made in the rER.
• Packaged in the Golgi apparatus, and secreted via vesicles which merge with the apical membrane to release only their contents into the duct system.

Question 35

What is the process of secretion of protein in milk known as?

Answer 35

Merocrine secretion – aka exocytosis

Question 36

Following menopause, what happens to the breast?

Answer 36

The secretory cells of the TDLU’s degenerate, leaving only ducts.
In the connective tissue, there are fewer fibroblasts and reduced collagen and elastic fibres.