4/15 Breast Dev/Lactation Flashcards
location of breasts
located in superficial fascia overlying pectoralis fascia, btwn 2nd rib and 6th intercostal space, with tail of Spence extending into axilla
what are the ligaments of cooper?
tissue condensations that support the breast
Arterial, Venous, and Lymphatic Supply of the breast?
- Arterial supply: internal mammary a., intercostal a., axillary a., lateral thoracic a.
- Venous drainage: axillary v., intercostal v., internal thoracic v.
- Lymphatic drainage: axillary, parasternal, and clavicular nodes
What is the breast architecture?
Compound tuboalveolar glandd surrounded by adipose tissue, loose interlobar connective tissue (stroma)
Compound tuboalveolar gland:
- alveoli, combine to form
- lobuli, combine to form
- lobes, drained by
- lactiferous ducts (15-25, one for each lobe), combine to form
- lactiferous sinuses (when compressed, it squeezes the milk into the baby’s mouth)
What is the milk factory of the breast?
What stimulates the production of milk?
- alveolar cells
- make up single layer of secretory cells forming sac-like structure surrounded by myoepithelial cells and a capillary network.
- stimulated by prolactin; each one is a “milk factory”
- myoepithelial cells – stimulated by oxytocin
- make up single layer of secretory cells forming sac-like structure surrounded by myoepithelial cells and a capillary network.
What tissue is breast derived from?
sweat glands (some say sebaceous gland); comes from ecto/mesoderm
How are breasts formed?
Ectoderm:
- mammary ridge/crest (milk line) forms @ 4-5 wks; develops into epithelial nodules at 5-7 mos
Mesoderm:
- “mesenchymal induction” - ectoderm induces mesoderm to form SM, CT, and BV
- epithelial nodules starts as buds -> cords -> ducts and elevates nipple and areola
What is “mesenchymal induction”?
“mesenchymal induction” - ectoderm induces mesoderm to form SM, CT, and BV
T/F like the reproductive system of M/F, the breast is also the different btwn M/F at birth
FALSE
M & F breasts are identical at birth - rudimentary nipple and ductal system, not much stroma, somatic growth only
What happens at thelarche (8-14)
What hormones are involved?
- increase size during adolescence
- Estrogens – stimulates growth of lactiferous ducts
- Progesterone – cause ducts and lobular alveolar units formation
- Fat accumulates btwn lobes, duct branching and elongating, terminal buds
- Nipples and areola enlarge and become pigmented
How does the breast change during the menstrual cycle?
- Progesterone/ luteal phase: proliferation of ductal system, slight lobular-alveolar development, increased vascularity, some edema (due to increased vascularity) and tenderness (one sx of PMS)
- Estrogen (proliferative) phase: regression of edema postmenstrually
T/F breasts are in a “resting phase” until pregnancy & lactation.
True. It becomes a fully developed organ
What happens to the breast during menopause?
- slow atrophy of lobulo-alveolar tissues
- prior to menopause, there is glandular tissue that may result in higher rate of false (+) mammograms
3 stages of lactogenesis?
STAGE I - PREGNANCY
STAGE II - POSTPARTUM
STAGE III - LACTOPOIESIS (maintenance of established milk secretion)
What happens during the first stage of lactogenesis?
STAGE I - PREGNANCY
- breast composition changes from mostly stromal (fat) cells , 1st tri –> glandular tissues , 2nd tri
- mid pregnancy and on: alveolar cells differentiation (and secretion into alveoli) +** **leukocyte infiltration
*
What are the prerequisites for initiation of milk secretion?
- fully developed mammary gland
-
withdrawal of estrogen and progesterone -> releases inhibition of lactose synthesis in alveolar cells, PRL binding sites, glucocorticoid binding sites
- note: E&P from the placenta inhibit lactose synthesis in alveolar cells during gestation; delivery of placenta releases this inhibition
- Insulin and thyroxine are permissive (??)
What prevents milk secretion during gestation?
- E&P from the placenta inhibit lactose synthesis in alveolar cells during gestation
- delivery of placenta releases this inhibition
What changes occur during stage II of lactogenesis?
STAGE II - POSTPARTUM
- incr. mammary blood flow
- incr. uptake of glucose and oxygen by breast cells in the alveoli
- incr. alveolar cell size and in number of secretory organelles
- Distension of alveoli with incr. milk production
What happens during stage III of lactogenesis?
STAGE III - LACTOPOIESIS (maintenance of established milk secretion)
- Suckling -> PRL + oxytocin release
- (feedback) PRL -> decr. dopamine -> incr PRL -> casein mRNA -> milk proteins/sugars production in alveolar cells
- oxytocin -> myoepithelial cell contraction to expel milk from the lactiferous sinus (“let down”)
What happens if the alveoli is not emptied of its milk?
overtime, the fluid pressure in the alveoli causes the alveoli cells to die, ultimately decreasing milk supply. Once the feedings are spaced out longer, milk production drops
How does the alveolar cell produce milk?
Under the influence of PRL:
- Cellular production - lactose and proteins are produced and secreted via exocytosis pathways into lumen; creates an osmotic gradient that draws water into the lumen
- fat globules are excreted into the lumen as well
- pinocytosis-exocytosis of immunoglobulins allows for vertical transmission of immunity
- Paracellular pathway transport of proteins = allows for maternal leukocytes and plasma components to enter milk (vertical passive transfer)
Breast milk is the gold standard, but what two supplements must you provide?
there is not a lot of Fe or Vitamin K, therefore these must be given as a supplement or shot, respectively, to assist with clotting
How does breast milk composition change with feeding?
- Beginning of feeding = richer in sugars + proteins
- End of feeding “hind milk” = richer in fat
Why is breast milk the gold standard?
- Unique composition – current baby formulas have major differences in the total quantities and qualities of proteins, carbohydrates, and fats when compared with human milk and they also contain numerous additives
-
Immune function - breast milk contains maternal
- macrophages, other leukocytes
- immunoglobulins - secretory IgA > IgG
- lactoferrin – protein in PMNs that inhibits microbial growth via iron chelation (bacteriostatic)
- Improved health outcomes - optimal development of brain, organs, better somatic growth, physiologic development, enhanced cognitive development and higher IQ, decrease risk of cancers or chronic diseases (DM, HTN, obesity)
contraindications of breast feeding?
- AIDS
- Active TB
- Use of street drugs, uncontrolled EtOH intake
- Breast cancer treatments
- Rx: antineoplastics, thyrotoxic, immunosuppressives
- Infant with galactosemia
The most common obstacle to successful lactation in the US is:
- Poor latch either because of baby or mom’s anatomy
- Lack of supportive family - “the mother in law effect”
- Lack of knowledgeable medical providers/hospital practices that may adversely effect lactation
- Society’s view of the breast as a sex object
How can you improve breast feeding rates?
- Educate hospital staff about lactation
- Review and change hospital policies and procedures to create breastfeeding supportive systems
- Decrease influence of infant formula in the hospital setting
