SM_195b: Breast Development, Pregnancy, Lactation, and Benign Breast Flashcards
Describe 5th week of fetal breast development
Fetal breast development: 5th week
- Bilateral ectodermal ridges originating from the axilla to the inguinal region develop into 15-20 buds
Describe 7th week of fetal breast development
Fetal breast development: 7th week
- Buds undergo apoptosis except for a single pair at thr 4th-5th intercostal space called the primary mammary buds
- Breast development as these buds penetrate into underlying mesoderm
Describe 12th week of fetal breast development
Fetal breast development: 12th week
- Primary buds develop into secondary buds which will eventually form into mammary lobules
Describe 20th week of fetal breast development
Fetal breast development: 20th week
- Mammary ridge penetrates the mesoderm sending radial ingrowths into the breast
- Areola begins to develop
Describe fetal breast development during 2nd and 3rd trimesters
Fetal breast development: 2nd and 3rd trimesters
- Sweat, sebaceous, and apocrine glands develop into Montgomery glands
- Lumina develop within the mammary buds developing into the lactiferous ducts, a mammary pit, and eventually a nipple in infancy
Describe breast development after birth
Breast development after birth
- Protrusion of the nipple and development of terminal ducts
Describe congenital abnormalities of the nipple
Congenital abnormalities of the nipple
- Polythelia: accessory nipples
- Athelia: absence of the nopples
- Polymastia: supernumerary breast
- Retracted or inverted nipple: due to failure of full development of the nipple
- Amastia: absence of the breast, usually unilateral
- Micromastia: excessively small breast
- Poland syndrome: unilateral underdevelopment of pectoralis muscle and breast
- Macromastia / virginal hypertrophy: diffuse hypertrophy of one or both breasts
- Anisomastia: significant size difference
- Symmastia: medial confluence of the breast
Polythelia is ____
Polythelia is accessry nipples
(Particularly common in Asian women)
Retracted or inverted nipples result from ___
Retracted or inverted nipples result from failure of full development of the nipple
Poland syndrome is ____
Poland syndrome is unilateral underdevelopment of pectoralis muscle and breast
Anisomastia is ____
Anisomastia is significant size difference between breasts
Describe normal breast development
Normal breast development
Puberty begins between ages 8-12 years
- Hypothalamus -> GnRH
- GnRH -> FSH and LH from pituitary
- FSH and LH -> maturation of ovarian follicles
- Production of estrogens
- Mammary duct epithelium and stroma proliferate under ovarian estrogen: terminal duct lobules, collecting ducts, and breast buds proliferate
- Vascular and connective tissue proliferate -> increased breast size
Describe what complete breast development requires
Complete breast development requires
- Insulin, cortisol, thyroxine, prolactin, and GH
- Normal menstrual cycles: adequate body fat (16-24%), adequate sleep (gonadotropins released during sleep cycles)
- Exposure to sunlight: optimizes pituitary secretion of gonadotropins
Breast development stops ____
Breast development stops 2 years after onset of menarche
____ are used to categorize breast development
Tanner’s breast development stages are used to categorize breast development
Tanner Stage 1 (preadolescent) breast development is ____
Tanner Stage 1 (preadolescent) breast development is papilla elevation above the level of the chest wall
Tanner Stage II (breast budding) breast development is ____
Tanner Stage II (breast budding) breast development is breast and papilla elevation along with increased areola diameter
Tanner Stage III breast development is ____
Tanner Stage III breast development is ongoing enlargement of the breasts and areola
Tanner Stage IV breast development is ___
Tanner Stage IV breast development is elevation of the areola and papilla above the breast mound
Tanner Stage V (mature breast) breast development is ____
Tanner Stage V (mature breast) breast development is elevation of the papilla with regression of the areola
Breast ____ stops approximately 2 years after puberty
Breast development stops approximately 2 years after puberty
Breast ____ continues until approximately age 30 or during pregnancy to prepare for lactation
Breast maturity continues until approximately age 30 or during pregnancy to prepare for lactation
Radiation to the breast ___ can damage immature stem cells and increase risk of breast cancer
Radiation to the breast prior to age 30 can damage immature stem cells and increase risk of breast cancer
(minimal effect after age 30)
Describe breast anatomy
Breast anatomy
Tomosynthesis is ___
Tomosynthesis is an advanced form of mammography that can be used to screen for early signs of breast cancer in women with no symptoms
Describe breast anatomy
Breast anatomy
Describe tissue of breast
Breast tissue
- Skin
- Subcutaneous tissue
- Breast tisusue: epithelial tissue (ducts, lobules), stroma (adipose, fibrous connective tissue)
Fatty breasts are ___
Fatty breasts are 0-25% breast tissue