Flashcards in Breast Dev + Phys Deck (39)
How long does the AAP recommend breastfeeding newborns for?
- nutritional and health advantage
How is having your first child protective against having breast cancer (timeline)?
First 10 years following first birth
- increased risk for breast cancer
Then having a baby is protective in later years
- earlier you have a kid, sooner it kicks in?
How is breast feeding beneficial to the baby?
1. reduced incidence of infectious diseases
2. Reduced post natal infant mortality rates
3. Decreased incidence of SIDS
4. Improved cognitive fxn
Breast feeding benefits for mom
1. Decreased postpartum bleeding and more rapid uterine involution
2. Decreased menstrual blood loss and increased child spacing
3. Earlier return to pre-pregnancy weight
Lobes of the breast
- what are they
- what are they composed of?
glandular units of the breast
- composed of multiple lobules containing alveoli (milk producing units)
- Milk ducts form multiple lobes feed into the nipple
- Glandular structures during lactation are the most prominent component of breast (62%) (when non lactating, intraglandular fat is largest at 49%) - 3 fold increase
Describe breast anatomy from stroma --> nipple
Stroma --> Lobules --> Terminal duct -->
Major duct --> Lactiferous sinus --> Nipple
Non lactating breast is mainly composed of what?
Intraglandular fat (49%)
*vs lactating breast have more glandular structures (62%)
Lactation cycle and how architectural changes occur (list the 5 distinct secretory pathways)
1. Glandular morphogenesis -->
2. Secretory differentiation -->
3. Lactation -->
4. Involution - apoptosis, glandular regression and return to quiescence
Embryonic development of breast
1. Ectodermal origin -->
2. Invaginates into underlying mesenchyme -->
3. Starts off as primary bud -->
4. Becomes secondary bud -->
5. Invaginates into fat pad
What induces differentiation of dermal mesenchyme to mammary mesenchyme?
What happens if it isnt present?
PTHrP secreted by epithelial cells.
- without it, no dermal mesenchymal condensation occurs and no differentiation into to mammary mesenchyme
- Mammary mesenchyme doesnt develope and secrete signals to stimulate nipple formation --> primary bud epithelial cells regresses
Blomstrands chondroplasia (amastia)
absence of PTHrP --> primary bud epithelial cells regresses --> no nipple or mammary morphogenesis
Mom's Elevated prolactin and decreased progesterone at parturition can induce what in the infant?
Hormonal changes act on baby (a little bit)
- temporary milk secretion in both male and female neonates (witches milk)
How long do progesterone receptors present in glandular elements in the neonate last for?
3 months after birth
- Temporary GnRH driven spike in progesterone during infancy stimulates branching and lobule fxn
What elaborates in puberty?
Ductal morphogenesis --
- driven by E (principal regulator) and P
- macroscopic breast development ends at age 15, but fxnal development continues on
Formation of ductal network and lobules are regulated ______
- by two different ovarian hormones
Which phases of the menstrual cycle/hormones do the alveoli and ducts primarily mature in?
Ducts: Around ovulation
- E in combo with GH induce elongation and branching of the ductal network by increasing IGF-1 production by stromal cells
- E is just the activator, IGF-1 is the money maker
Alveoli: secretory phase (Progesterone)
- P during the luteal phase brings about side branching and lubulo-alveolar development
During pregnancy, which morphogenesis occurs?
- associated with secretory differentiation
- initiation of milk protein expression and development of secretory capacity
- copious milk production
What is essential for producing a robust side branching of lobuloalveolar formation
Prolactin + progesterone
*progesterone alone not enough for formation of mature alveoli ***
- Milk product synthesis is initiated during pregnancy by the actions of prolactin or placental lactogen but milk secretion is held in check by high progesterone levels
- Milk product synthesis is initiated during pregnancy by the actions of ______ or ______ but milk secretion is held in check by high ______levels
Milk secretion is initiated by the fall in ____ at parturition.
(due to removal of placenta!)
(remember progesterone holds milk secretion in check)
- even if a small amt of placenta is left behind, woman will not be able to lactate
Elevated prolactin levels is required to:
maintain milk synthesis and secretion
Pituitary kicks in and makes more prolactin
How does suckling allow for lactation?
1. Suckling stimulated afferent activation of the hypothalamus
2. Hypothalamic regulated production and release of prolactin and oxytocin
- inhibits hypothalamic DA release --> no more inhibition of prolactin
3. Prolactin/Oxytocin mediated secretion and ejection
*prolactin is normally inhibited by DA
Which hormone is involved in:
1. Milk removal
2. Milk ejection
1. Milk removal: prolactin (milk synthesis and secretion)
2. Milk ejection: oxytocin
*milk removal is required to maintain glandular integrity and milk production
INfant suckling leads to downregulation of what?
DA and GnRH
- women who are lactating are less likely to get pregnant
Suckling is required to maintain _____ levels. Failure to initiate breastfeeding shortly after parturition diminishes what?
- failure to initiate breastfeeding shortly after parturition diminishes PROLACTIN signaling and impairs milk synthesis and secretion
-Particular problem for women that deliver preterm infants --> milk production capacity of the mother and suckling ability of the infant are both immature
Particular lactation problem for women that deliver preterm infants
milk production capacity of the mother and suckling ability of the infant are both immature
Milk ejection requires _____ to be squeezed, and _____ to be released.
alveoli (by myoepithelial cells)
- oxytocin is also required for milk ejection: stimulates contraction of myoepithelial cells that form a basket-like network around alveoli
Suckling stimulates synthesis and release of oxytocin from hypothalamic neurons
Factors negatively affecting lactation
2. Delayed lactation initiation
3. Pituitary disorders or damage
4. Excessive weight
How does excessive weight affect lactation
Decreased ability to initiate lactation and maintain lactation
- Produce less prolactin
- cannot efficiently mobilize energy for lactation
(fat is selfish)