Breast Histology Flashcards
What is the breast?
A subcutaneous gland
What is the secretory tissue of the breast made up of?
15-25 lobes
What do breast lobes consist of?
A compound tubule-acinar gland which drains via a series of ducts leading to the nipple
What is found adjacent to secretory lobules in the breast? Then what is this surrounded by?
Dense fibrous tissue
Adipose tissue
What is found amongst fibrous CT in the breast?
Some larger condensations that extend from the dermis of the skin to the deep fascia overlying the muscle of the anterior chest wall
‘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?
Suspensory ligaments
Where in the breast do you find most suspensory ligaments?
In the upper breast.
What do suspensory ligaments in the upper breast do?
Support the breast tissue
What is the basic functional secretory unit of the breast?
The Terminal Duct Lobular Unit (TDLU)
In the non-lactating breast, what do terminal ductules lead into?
An intralobular connecting duct
What do interlobular connecting ducts lead into?
The lactiferous duct for that lobe
What does the lactiferous duct for that lobe lead into?
The nipple, passing through an expanded duct region near the nipple, termed the lactiferous sinus
Within the lobule, what line the acini?
Secretory epithelial cells
What do secretory epithelial cells vary from?
Cuboidal to columnar
What are the secretory cells of the acinus surrounded by?
Myoepithelial cells (MEp). (appear pink in pic)
What are myoepithelial cells?
Contractile epithelial cells
What are myoepithelial cells surrounded by?
The basal lamina
What are larger ducts – such as a lactiferous duct – lined by?
An epithelium that varies from thin stratified squamous to stratified cuboidal.
What is the surface of the nipple like?
Wrinkled
What is the surface of the nipple covered by?
A thin, highly pigmented keratinized stratified squamous epithelium.
What does the nipple covering have a core of?
Dense irregular connective tissue, mixed with bundles of smooth muscle
Describe what type of epithelium lactiferous ducts are lined by.
- Near the surface – stratified squamous epithelium.
- Deeper – stratified cuboidal epithelium.
- Deeper still – duct lining may become only one cell thick.
What are also present on the skin of the breast?
Sebaceous glands
During the menstrual cycle, changes occur in the breast even in the absence of pregnancy. Describe these.
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.
If pregnancy occurs, dramatic changes take place in the breast:
What happens in the 1st trimester?
There is elongation and branching of the smaller ducts, combined with proliferation of the epithelial cells of the glands and myoepithelial cells
If pregnancy occurs, dramatic changes take place in the breast:
What happens in the 2nd trimester?
Glandular tissue continues to develop, with differentiation of secretory alveoli.
Also, plasma cells and lymphocytes infiltrate the nearby connective tissue
If pregnancy occurs, dramatic changes take place in the breast:
What happens in the 3rd trimester?
Secretory alveoli continue to mature, with the development of extensive rER.
What are all the changes in the breast during pregnancy accompanied by?
A reduction in the amount of connective tissue and adipose tissue present
During pregnancy, what do oestrogen and progesterone stimulate (in relation to the breast)?
Proliferation of secretory tissue
During pregnancy, what becomes sparse in the breast?
Fibro-fatty tissue
Outline the approximate composition of human milk.
- 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
Explain how lipid droplets are secreted in breastmilk.
Secreted surrounded by a membrane, carrying a small amount of cytoplasm with it (budding)
Secreted surrounded by a membrane, carrying a small amount of cytoplasm with it (budding). What is this form of secretion known as?
APOCRINE secretion
What are the proteins in milk made in? Describe what then happens to them, including how they are secreted.
- 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.
What is the process of secretion of protein in milk known as?
Merocrine secretion – aka exocytosis
Following menopause, what happens to the breast?
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.
