The Breast

Question 1

What hormones are required for complete mammary growth and differentiation

Answer 1

• LH and prolactin from the anterior pituitary. Influence growth of the nipple
• human placental lactogen = responsible for ducal development and differentiation
• oestrogen and progesterone = from the ovaries and placenta. The sex hormones are responsible for lobe and lobule development. Widening of ducts to allow secretory function
• adrenocorticotrophic hormone and human growth hormone from anterior pituitary. Combined with prolactin and progesterone promotes mammary growth

Question 2

The timeline of breast development

Answer 2

Occurs from embryonic/fetal life all the way through to pregnancy and lactation. Breast structures will continue to bud until the age of 35 years

Differentiation between males and females occurs at puberty when differences in hormonal signalling will give rise to the biological differences between the two sexes

Question 3

Mammogenesis at 4 gestational weeks

Answer 3

Two milk lines/streaks from axils to groin (thickening of epithelial cells - line of glandular tissue)

Question 4

Mammogenesis at 7-8 weeks

Answer 4

Milk hills stage = thickening and inward growth into the chest wall of the developing embryo

Question 5

Mammogenesis at 12-16 gestational weeks

Answer 5

Differentiation into smooth muscle cells of nipple and areola
Epithelial cells develop mammary buds which branch in a tree-like pattern - create alveoli of the glands

Question 6

Mammogenesis at 28 - 32 weeks

Answer 6

Canalisation of branched epithelial tissue
Primary milk ducts by 32 weeks of gestation

Question 7

Mammogenesis at 32- 40 weeks

Answer 7

Lobular alveolar structures constraining colostrum will begin to develop = witches milk produced by baby

Ducts open into area which becomes the nipple
The nipple and areola develop and become pigmented

Question 8

What type of growth is experienced by females in childhood vs puberty

Answer 8

Childhood = isometric growth = develop in same proportions as size of child

Allometric growth = specific changes due to influence of hormones from hypothalamus and anterior pituitary

By 10-12 yrs a girls breast has formed primary and secondary ducts which continue to grow and from club shaped termini

Question 9

Why do females experience breast discomfort in each reproductive cycle

Answer 9

Due to proliferation and active growth of mammary glands.

Size of the breasts/glandular tissue grow from puberty onwards under influence of oestrogen and human growth hormone

The shaped of breast is controlled by deposition of fat which is controlled by the release of oestrogens in the system

Question 10

What is the structural anatomy of the breast

Answer 10

Located between the 2nd rib and 6th intercostal space

Comprised of parenchyma and stroma

The nipple openings are continuous with lactiferous ducts which carry out the milk outwards from inside the glandular tissue

Glandular tissues can extend towards the axillary tail of Spence.

Question 11

What determines the functional capacity of the breast

Answer 11

The quality of the glandular tissue instead of the size of the breast is more important

Those with smaller breasts will produce the same amount of milk to feed child but will feed more regularly

Question 12

What is the basic secretory unit of the breast

Answer 12

Several alveoli make up a lobule which is connected via a lacterious duct

Each alveolus is made of many lactocytes and on the external border is a layer of myoepithelial cells (smooth muscle) = important in expulsion of milk

The alveoli are in close intact with capillaries - provides nutrients such vitamins and minerals from mothers digestive system

Question 13

What is the blood supply to the breast to meet its high metabolic demand in pregnancy and lactation

Answer 13

60% is from the internal thoracic/mammary artery
30% is from the lateral thoracic artery

Question 14

What is the nerve supply to the breast tissue

Answer 14

Branches from the 2nd to the 6th intercostal nerve

Question 15

What is a tubercle of Montgomery

Answer 15

The areola has openings to it and each one is connected to a tubercle of Montgomery

Within the tubercle there is a true mammary lobule structure and sebaceous glands (babies attach to breast more quickly (olfactory stimulation?)

Question 16

What occurs in the first stage of lactogenesis

Answer 16

In the first and second trimester: breast development allows for secretion of colostrum/first milk for premature delivery/lactation in miscarriage can be traumatic

Question 17

What occurs in the second stage of lactogenesis

Answer 17

1-5 days post birth

The baby will receive copious milk secretion regardless of whether mother wants to breastfeed or not

Question 18

What occurs in the 3rd stage of lactogenesis

Answer 18

Up to 6 months (maintenance of long term milk production)

Initially breast milk production is dependent on the release of prolactin to the mammary glands but later is dependent on concentrations of feedback inhibitor of lactation FIL. When the mother feeds this exits in the milk and therefore concentrations of this reduces

Question 19

How much should young infants be fed in a 24 hour period

Answer 19

8-12 times

Question 20

What happens of the levels of major hormones after birth

Answer 20

Oestrogen and progesterone drops

Oxytocin and prolactin levels rise in response to touch, smell and sight of the baby

Question 21

What constitutes the prolactin receptor theory and how does this explain how milk is produced

Answer 21

Sensory stimulation such as suckling relays information to the hypothalamus which sends prolactin releasing hormones to the anterior pituitary such as
- vasoactive intestinal polypeptide
- oxytocin

Prolactin arrives at breast and binds to its receptor on the lactocyte
More suckling = greater affinity for binding to receptor
Prolactin receptors bind prolactin more effectively when alveoli are empty and as alveoli fill with milk the receptors undergo conformational change which reduces binding affinity

Question 22

The hypothalamus Down regulates which hormones which inhibit prolactin secretion

Answer 22

Dopamine

Question 23

Actions/roles of prolactin

Answer 23

Responsible for milk production

Responsive to touch and stimulation

Levels are higher at night

Frequent contact/feeds sets up long term production

Question 24

Actions/roles of oxytocin

Answer 24

Responsible for milk delivery

Acts on muscle cells in pulsatile action

Levels are higher when the baby is near

Stress can temporarily delay the let down reflex

Question 25

Other benefits of oxytocin on the body

Answer 25

Works on our feelings and emotions (proximal to the amygdala nucleus)

Lowers BP and improves sleep

Reduces stress by taking on cortisol

Reduces pain sensitivity

Boosts our immune system

Question 26

How does breast milk differ from formula milk in composition

Answer 26

Formula milk = vitamins and minerals, water, proteins, carbs, fats

Breast milk = vitamins and minerals, water, proteins, carbs, fats,
In addition:
- oligosaccharides
- antibodies (IgG) + IgA and maybe IgM
- hormones
- white blood cells
- viral fragments
- enzymes
- anti-inflammatory molecules
- transfer factors
- bifidus factor

Question 27

Role of secretory IgA in breast milk

Answer 27

Coats the gut to protect against foreign antigens and hypersensitivity reactions

Question 28

Role of transfer factors in breast milk

Answer 28

Assists the baby to absorb nutrients such as lactoferrin for iron

Question 29

What is the role of bifidus factor

Answer 29

Facilitates the growth of lactobacillus bifidus which creates an acidic environment (bacteria prefer high pH)

Question 30

Role of oligosaccharides

Answer 30

Simple carbohydrates which prevent pathogens from adhering to gut wall

Question 31

Breastfeeding pathologies are mostly caused by which three causes

Answer 31

• poor positioning and attachment
• nipple issue or trauma
• breastfeeding management problems

Question 32

What is most common cause of unilateral mastitis

Answer 32

Inadequate milk removal/ milk stasis which causes back pressure and leaking into the interstitial spaces through paracellular pathways
This triggers an inflammatory response

Question 33

What are the symptoms of infective mastitis and non-infective mastitis

Answer 33

Red swollen area that may be painful to touch

Infective signs:
- same as above but pyrexia
- severe flu-like symptoms and rigours
- sometimes discharge from nipple that is pus or blood

Question 34

What are common causative agents of infective mastitis

Answer 34

Staphylococcus aureus

Sometimes maybe streptococcal or E.coli

Question 35

Management of mastitis (infective)

Answer 35

Analgesia and antibiotics (penicillinase resistant penicillins and cephalosporins)

Bed rest

Increased fluid intake for mother

Frequent breastfeeds for the baby

Correct positioning and latching

Question 36

What is a complication of infective mastitis if it is not managed at all or poorly managed

Answer 36

Can lead to the formation a breast abscess
Would require incision and drainage