Week 7 - A - Histology of the Breast - Lobes/Terminal duct lobular units, ducts, apocrine and merocrine secretion Flashcards
The breast is a subcutaneous gland. How many lobes does a breast consist of?
The secretery tissue of the breast is made up of 15-25 lobes
The secretory tissue of the breast is made up of 15-25 lobes, each consisting of a compound tubulo-acinar gland which drains via a series of ducts leading to the nipple. What is each lobe made up of? When are the ducts draining the lobes of the mammary glands known as?
Each lobe is made up of lobules - the terminal ducts draining from each lobe form lactiferous ducts which drain the lobes of the breast
What do the lactiferous ducts form just posterior to the nipple?
The lactiferous duct leads to the nipple, passing through an expanded duct region near the nipple termed the lactiferous sinus The lactiferous sinus is a dilated portion of the duct which is also known as the AMPULLA
The breast is composed of mammary glands surrounded by a connective tissue stroma. What type of glands are the mammary glands? What do the consist of?
The mammary glands are modified sweat glands They consist of a series of ducts and 15-25 secretory lobes Many lobules come from the lobe
Amongst the fibrous connective tissue are some larger condensations that extend from the dermis of the skin to the deep fascia overlying the muscle of the anterior chest wall. What are these known as and where are they most pronounced?
These are the suspensory ligaments of the breast and they are most prominent in the upper breast
What is thought to be the function of the suspensory ligaments of the breast? What is the other name for the suspensory ligaments of the breast?
They are though to have the function of supporting the breast They are also known as suspensory ligaments of cooper
What is the basic functional secretory unit of the breast?
This is the terminal duct lobular unit
What does the terminal duct lobular unit consist of?
TDLU (terminal duct lobular unit) - this consists of the lobe, as well as the intralobular duct (temrinal ducts drain into the intralobular duct) which drains into the extralobular duct and into the lactiferous duct
What does the lactiferous ducts continue to form? Extralobular ducts drain into the lactiferous ducts
They continue to form lactiferous sinus which is an expanded portion of the lactiferous duct before the sinus open into the nipple
What do the acini of the breast contain?
The acini in each lobule contains the secretory epithelial tissue - the acini line each lobule of the lobe
What hormone stimulates the acini which contain the secretory epithelial cells?
This would be prolactin Within the lobes, you have lobules The lobules are lined by acinar cells which have the secretory epithelium
The secretory cells of the acini are surrounded by contractile cells which respond to which hormone? What are these contractile cells known as?
These contractile cells are known myoepithelial cells and respond to oxytocin
What type of epithelium covers the surface of the nipple? What does the core of the nipple contain?
The surface of the nipple is lined by highly keratinized stratified squamous epithelium The core of the nipple contains dense irregular connective tissue mixed with bundles of smooth muscle
If pregnancy occurs, dramatic changes to the mammary gland take place When is the increase in breast size most rapid? What happens in the first semester?
The increase in breast size is most rapid during the 1st 8 weeks of pregnancy In first trimester, there is the elongation and branching of the smaller ducts combined with the proliferation of the epithelial cells of the glands and the myoepithelial cells
- * In the first trimester there is elongation and branching of the smaller ducts, combined with proliferation of the epithelial cells of the glands and the myoepithelial cells.
- * In the second trimester glandular tissue continues to develop with differentiation of secretory alveoli. Also, plasma cells and lymphocytes infiltrate the nearby connective tissue.
- * In the third trimester secretory alveoli continue to mature, with development of extensive rER.
What are these changes accompanied by the reduction of?
These changes are accompanied in the reduction of the amount of connective tissue and adipose tissue present in the breast - ie major increase in functioning secretory breast tissue and decrease in non secretory functioning
What are the two main components of breast milk?
88% water 7% carbohydrates (mainly lactose)
Describe hwo both lipids and proteins are secreted again?
Lipid droplets are secreted surrounded by a membrane and carrying a small amount of cytoplasm - apocrine secretion Proteins are produced in rER, packaged in golgi apparatus & secreted via vesicles which merge with the apical membrane to release only their contents - merocrine secretion or exocytosis
Following the menopasuse, what happens to the terminal duct lobular units?
Following menopause the secretory cells of the TDLUs degenerate leaving only the ducts
