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 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)
