Breast development

Question 1

What is mammogenesis?

Answer 1

The growth and development of the breast

Question 2

What is lactogenesis?

Answer 2

The functional changes that allow for milk secretion

Question 3

What are the two stages of lactogenesis?

Answer 3

Secretory differentiation and secretory activation

Question 4

Describe secretory activation

Answer 4

Its the onset of mature milk secretion that occurs 3-8 days after birth causing the volume of milk secreted to increase to 0.75-1L of milk per day.

Question 5

What triggers secretory activation?

Answer 5

Triggered by a reduction in progesterone (caused by loss of placenta) in presence of prolactin (which stimulates milk production)

Question 6

Describe secretory differentiation

Answer 6

Glands become sufficiently differentiated to secrete colostrum, this occurs in mid-pregnancy (about 16 weeks) until a few days after birth. Causes only a few ml of colostrum to be secreted

Question 7

What triggers secretory differentiation?

Answer 7

Reduction in oestrogen

Question 8

Which 4 hormones increase to stimulate mammogenesis and what are their functions?

Answer 8

1. Oestrogen-
   Causes growth and branching of the ductal system (where milk is stored)
   Enables fat storage in stroma - Inhibits milk production
2. Progesterone - Causes lobule growth and increases the number of alveolar cells (where milk is produced)
3. Human Placental lactogen (produced by placenta) AND Prolactin (secreted by pituitary gland) - both cause the development of secretory characteristics in alveolar cells (milk is secreted by exocytosis)

Question 9

3 other results of mammogenesis

Answer 9

1. Breasts enlarge due to alveolar lobular formation
2. Subcutaneous veins enlarge to become more prominent.
3. Areolar darkens and montgomery glands (bumps on areola) produce lipoid fluid to moisturise the nipple

Question 10

Describe galactopoiesis

Answer 10

Maintains milk production from 9 days after birth

Question 11

Describe the stages of galactopoiesis

Answer 11

1. Milk is continually secreted into alveoli and if it isn’t removed it accumulates which triggers a feedback inhibitor of lactation. Milk is stimulated to be ejected by oxytocin and the effect of milk ejection is a positive feedback loop for the baby to keep suckling.

Question 12

How is milk secretion controlled

Answer 12

Initially it is endocrine (oxytocin) but becomes more local autocrine

Question 13

Define involution

Answer 13

Termination of milk production (decrease in size of breast with associated decrease in milk production)

Question 14

Whens does involution occur?

Answer 14

Normally 40 days after the last breastfeed

Question 15

Describe the process of involution

Answer 15

1. Alveolar cells shrink and lose their secretory function due to accumulation of inhibitory peptides. 2. Epithelial cells no longer require secretory functions so are removed by apoptosis and replaced by adipocytes

Question 16

What is the fundamental secretory unit of the breast and what is it surrounded by

Answer 16

Alveolus (surrounded by contractile myoepithelial cells and adipose cells)

Question 17

Describe gross anatomy of breast ducts

Answer 17

Alveloi arrange into secretory lobule which drains into a ductule which drains into a lactiferous duct

Question 18

Which hormone causes milk production

Answer 18

Prolactin

Question 19

Which hormone stimulates milk ejection

Answer 19

Oxytocin (causes myoepithelial cells within mammary glands to contract)

Question 20

What effect does longer intervals between feeds have on fat content

Answer 20

Decreases fat content

Question 21

When is breast milk fat content highest

Answer 21

Mid-morning (lowest overnight)

Question 22

Primary role of colstrum

Answer 22

Immunological - contains high amounts of white blood cells and antibodies (especially IgA which coats lining of intestines in infants)

Question 23

Composition of colostrum

Answer 23

High conc proteins, growth factors, antimicrobial products and electrolytes
Low conc fat, carbs

Question 24

Whey/casein ratio in mature milk

Answer 24

60:40

Question 25

Carbohydrates present in mature breast milk

Answer 25

High lactose

Human milk oligosaccharides (i.e. probiotics to nourish gut flora)

Question 26

Fat composition in mature breast milk

Answer 26

Mainly triglycerides
Carry fat soluble vitamins
Fat content increases throughout feeding sessions

Question 27

Vitamins and mineral in breast milk

Answer 27

Low conc but efficiently absorbed

Question 28

5 benefits of breast milk

Answer 28

1. Reduces uterine bleeding
2. Reduces risk of breast cancer
3. Reduces risk of ovarian cancer
4. Improved birth spacing (due to lactational amenorrhea)
5. free and available

Question 29

state 3 things that determine a good latch

Answer 29

1. Infants mouth wide open
2. Mothers nipple against the roof of the infants mouth
3. Infants tongue against the bottom of the areola

Question 30

What is the difference in in presentation between sore/cracked nipple and a carnival infection?

Answer 30

With sore/cracked nipple there is severe nipple pain when the infant is suckling whereas with candid infection the pain continues between feeds