Breast Dev + Phys Flashcards
How long does the AAP recommend breastfeeding newborns for?
6 months
- 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?
- reduced incidence of infectious diseases
- Reduced post natal infant mortality rates
- Decreased incidence of SIDS
- Improved cognitive fxn
Breast feeding benefits for mom
- Decreased postpartum bleeding and more rapid uterine involution
(oxytocin) - Decreased menstrual blood loss and increased child spacing
(lactational amenorrhea) - Earlier return to pre-pregnancy weight
Lobes of the breast
- what are they
- what are they composed of?
- Importance?
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)
Get pregnant:
- Glandular morphogenesis –>
- Secretory differentiation –>
- Lactation –>
- Involution - apoptosis, glandular regression and return to quiescence
Embryonic development of breast
- Ectodermal origin –>
- Invaginates into underlying mesenchyme –>
- Starts off as primary bud –>
- Becomes secondary bud –>
- 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 ______
independently
- 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?
Glandular morphogenesis
- associated with secretory differentiation
1. Lactogenesis-1 - initiation of milk protein expression and development of secretory capacity
2. Lactogenesis-2 - 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
Prolactin
placental lactogen
progesterone
Milk secretion is initiated by the fall in ____ at parturition.
Progesterone
(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?
- Suckling stimulated afferent activation of the hypothalamus
- Hypothalamic regulated production and release of prolactin and oxytocin
- inhibits hypothalamic DA release –> no more inhibition of prolactin - Prolactin/Oxytocin mediated secretion and ejection
*prolactin is normally inhibited by DA
Which hormone is involved in:
- Milk removal
- Milk ejection
- Milk removal: prolactin (milk synthesis and secretion)
- 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
