Breast anatomy and histology Flashcards
The secretory tissue of the breast is made up of ow many lobes? What do these consist of?
15-25 lobes
Each consist of a compound tubulo-acinar gland which drains via a series of duct leading to the nipple
What is adjacent to the secretory lobules of the breast?
Dense fibrous tissue, which in turn is surrounded by adipose tissue
Label this diagram
Where does the mammary gland extend vertically?
Extends vertically from the 2nd or 3rd to 6th rib
Where does the mammary gland extend horizontally / transversely?
From sternal edge, medially, almost to the midaxillary line laterally
Label this diagram
Label this diagram
Between the breast and the deep fascia is what?
Loose connective tissue (“submammary space”)
What does the submammary space allow for?
The breast some degree of movement on the deep pectoral fascia
The mammary bed lies superiorly to?
The mammary bed lies inferiorly to?
External oblique and its aponeurosis
What is the nipple?
Conical or cylindrical projection below the centre of the breast
Where does the nipple lie?
At level of 4th intercostal space in nulliparous females
What is the nipple pierced by?
15-20 lactiferous ducts
The nipple contains what kind of muscle?
Circular and longitudinally disposed smooth muscle
What is the areola?
Pigmented circular area of the skin around the base of the nipple
The outer margin of the areola contains what?
A number of modified sebaceous glands
The sebaceous glands at the outer margin of the areola enlarge during pregnancy and lactation, and are known as?
Tubercles of Montgomery
The skin of nipple and areola is devoid of?
Hair and subcutaneous fat
What is the 3 components of the mammary gland?
Glandular tissue - tublo-alveolar type and arranged in lobes
Fibrous tissue - supports lobes and forms numerous septa
Interlobar fatty tissue - makes the organ rounded in contour
Amongst the fibrous connective tissue of the breast, are some larger condensations that extend from the dermis of the skin to the deep fascia (pectoral fascia) overlying the muscle of the anterior chest wall. These are referred to as?
Suspensory ligaments of Cooper
Where are suspensory ligaments of Cooper most pronounced and what do they do?
Often most pronounced in the upper breast
Support breast tissue
Label this diagram
What does the glandular tissue of the breast consist of?
Consists of 15-20 pyramidal lobes
Each lobe of the glandular tissue is drained by?
Separate lactiferous ducts
Lobes are arranged in what manner in the breast?
Arranged in radiating manner, converge towards the areola where each duct dilates to form lactiferous sinus
Each duct of the glandular tissue drains?
A segmental system
Each segmental duct divides into number of?
Terminal ducts
From the terminal duct, numerous secretory glands do what?
Pouch out like a bunch of grapes
The area of the breast drained by one terminal duct is known as?
The lobule
What is the terminal duct lobular unit (TDLU)?
The basic functional secretory unit of the breast
In the non-lactating breast, terminal ductules lead into?
An intralobular collecting duct which leads into the lactiferous ducts for that lobe
The lactiferous duct leads to the? What does it pass through
Leads to the nipple, passing through an expanded duct region near the nipple termed the lactiferous sinus
Label this
Label this diagram
Within the lobule, the secretory epithelial cells line the acini and vary from?
Cuboidal to columnar
The secretory cells of the acinus are surrounded by?
Myoepithelial cells (MEp)
What are myoepithelial cells?
Contractile epithelial cells which in turn are surrounded by basal lamina
Larger ducts like the lactiferous ducts are lined by?
An epithelium that varies from a thin stratified squamous to stratified cuboidal epithelium
What is a supposed origin of the mammary gland?
The nipple has a wrinkled surface and is covered by what kind of epithelium?
A thin highly pigmented keratinised stratified squamous epithelium
What does the nipple have a core of?
A core of dense irregular connective tissue mixed with bundles of smooth muscle
What can you see here?
In longitudinal section, the lactiferous ducts can be seen in (a). As the duct approaches the surface, it becomes lined by stratified squamous epithelium, however deeper it is lined by stratified cuboidal epithelium (b). Deeper still the duct lining may become only one cell thick. Several sebaceous glands (arrows) are present, and in (c) it is clear that these end directly on the surface of the skin. The core of the nipple can be seen at (d), showing the fibrocollagenous tissue mixed with smooth muscle bundles.
During the menstrual cycle, changes occur in the breast even in the absence of pregnancy. During the luteal phase, what happens?
The epithelial cells increase in height, the lumina of the ducts becomes enlarged and small amounts of secretions appear in the ducts.
In the first trimester of pregnancy, what happens to the mammary gland?
In the first trimester there is elongation and branching of the smaller ducts,
combined with proliferation of the epithelial cells of the glands and the
myoepithelial cells.
In the second trimester of pregnancy, what changes to the mammary gland occur?
In the second trimester glandular tissue continues to develop with
differentiation of secretory alveoli. Also, plasma cells and lymphocytes
infiltrate the nearby connective tissue.
In the third trimester of pregnancy what changes occur in the mammary gland?
In the third trimester secretory alveoli continue to mature, with
development of extensive rER.
In pregnancy, aside from specific changes to the mammary gland in each trimester, what other changes accompany these?
These changes are accompanied by a reduction in the amount of connective tissue and adipose tissue present.
Which image is non-lactating and which one is lactating?
During pregnancy, oestrogen and progesterone stimulate what in the mammary gland?
What is the composition of human breast milk?
Different components of milk are secreted via different mechanisms. Describe lipid droplet secretion
Lipid droplets are secreted surrounded by membrane and carrying a small amount of cytoplasm with it - this form of secretion is known as apocrine secretion
The proteins in milk are 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. This is merocrine secretion (also termed exocytosis)
Following menopause, what happens to the mammary gland?
Following menopause, 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.
What is the blood supply to the breast?
What is the venous drainage to the breast?
What are the lymphatics to the breast?
The breast is innervated by what nerves?
By anterior and lateral branches of the 4th to 6th intercostal nerves, which carry sensory and sympathetic efferent fibres
The nipple is supplied from the?
Anterior branch of the lateral cutaneous branch of T4
