Breast Embryology and Development Flashcards
Where do breasts initially develop from?
Ectoderm
When do breasts initially develop?
4th week of gestation
What happens in the 5th week of gestation?
Mammy bud becomes evident at the eventual site of the mammary gland
What happens in the 7-12th week of gestation?
Mammary bud branches several times that develop mammary lobules
What happens in the 20th week of gestation?
After continued lengthening and branching of the mammary buds, small lumina develop within the buds, which elongate to become the lactiferous ducts
What happens in the 3rd trimester of gestation?
Primary breast development (influenced by placental hormones)
What happens at term for breast development?
15-20 lobes of glandular tissue have developed
Where do supporting fibrous connective tissue develop from?
Mesoderm
What are 2 examples of supporting fibrous connective tissue?
- Cooper’s ligaments
- Fat
What does the ectoderm form?
Areolar
- surrounds the nipple during the 5th month of gestation
What 4 hormones play a role in breast development?
- Progesterone
- Estrogen
- Prolactin
- Placental lactogen
When does lactation begin? How does it happen?
- Begins after childbirth
- Progesterone levels decrease and the alveolar epithelium begins to secrete milk
What hormone causes contraction of the myoepithelial cells surrounding the alveoli forcing the alveoli to expel milk?
Oxytocin
Oxytocin is stimulated in response to what? (2)
Sucking or crying
What happens to the myoepithelial cells in menopause?
The glands involute and are replaced by fat and connective tissue
What causes the pituitary gland to initiate breast enlargement?
When the maternal estrogen decreases in the newborn
What is witch’s milk?
Fluid leaking from the nipple
- similar to colostrum
What hormone is secreted after ovulation? What organ secretes it? What is the effect?
- Progesterone is secreted
- From the ovary
- Increases breast size
When do the acini become fully formed and functional?
During pregnancy and lactation
What gets stimulated when progesterone decreases?
Lactation
