Breast development Flashcards
What is mammogenesis?
The growth and development of the breast
What is lactogenesis?
The functional changes that allow for milk secretion
What are the two stages of lactogenesis?
Secretory differentiation and secretory activation
Describe secretory activation
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.
What triggers secretory activation?
Triggered by a reduction in progesterone (caused by loss of placenta) in presence of prolactin (which stimulates milk production)
Describe secretory differentiation
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
What triggers secretory differentiation?
Reduction in oestrogen
Which 4 hormones increase to stimulate mammogenesis and what are their functions?
- Oestrogen-
Causes growth and branching of the ductal system (where milk is stored)
Enables fat storage in stroma - Inhibits milk production - Progesterone - Causes lobule growth and increases the number of alveolar cells (where milk is produced)
- 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)
3 other results of mammogenesis
- Breasts enlarge due to alveolar lobular formation
- Subcutaneous veins enlarge to become more prominent.
- Areolar darkens and montgomery glands (bumps on areola) produce lipoid fluid to moisturise the nipple
Describe galactopoiesis
Maintains milk production from 9 days after birth
Describe the stages of galactopoiesis
- 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.
How is milk secretion controlled
Initially it is endocrine (oxytocin) but becomes more local autocrine
Define involution
Termination of milk production (decrease in size of breast with associated decrease in milk production)
Whens does involution occur?
Normally 40 days after the last breastfeed
Describe the process of involution
- 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
What is the fundamental secretory unit of the breast and what is it surrounded by
Alveolus (surrounded by contractile myoepithelial cells and adipose cells)
Describe gross anatomy of breast ducts
Alveloi arrange into secretory lobule which drains into a ductule which drains into a lactiferous duct
Which hormone causes milk production
Prolactin
Which hormone stimulates milk ejection
Oxytocin (causes myoepithelial cells within mammary glands to contract)
What effect does longer intervals between feeds have on fat content
Decreases fat content
When is breast milk fat content highest
Mid-morning (lowest overnight)
Primary role of colstrum
Immunological - contains high amounts of white blood cells and antibodies (especially IgA which coats lining of intestines in infants)
Composition of colostrum
High conc proteins, growth factors, antimicrobial products and electrolytes
Low conc fat, carbs
Whey/casein ratio in mature milk
60:40
Carbohydrates present in mature breast milk
High lactose
Human milk oligosaccharides (i.e. probiotics to nourish gut flora)
Fat composition in mature breast milk
Mainly triglycerides
Carry fat soluble vitamins
Fat content increases throughout feeding sessions
Vitamins and mineral in breast milk
Low conc but efficiently absorbed
5 benefits of breast milk
- Reduces uterine bleeding
- Reduces risk of breast cancer
- Reduces risk of ovarian cancer
- Improved birth spacing (due to lactational amenorrhea)
- free and available
state 3 things that determine a good latch
- Infants mouth wide open
- Mothers nipple against the roof of the infants mouth
- Infants tongue against the bottom of the areola
What is the difference in in presentation between sore/cracked nipple and a carnival infection?
With sore/cracked nipple there is severe nipple pain when the infant is suckling whereas with candid infection the pain continues between feeds
