Anatomy and Histology Flashcards
the breast is a subcutaneous gland - describe the structure of a non-lactating breast?
the secretory tissue of the breast is made up of 15-25 lobes, each consisting of 15-25 lobes, each consisting of a compound tubulo-acinar gland which drains via a series of ducts leading to the nipple.
adjacent to the secretory lobules is dense fibrous tissue, which in turn is surrounded by adipose tissue.
what is the significance of suspensory ligaments within the breast?
support the breast tissue - more pronounced in upper breast
*the ligaments are larger condensations that extend from the dermis of the skin to the deep fascia overlying the muscle of anterior chest wall
is this slide a lactating or non-lactating breast?
non-lactating
what is the terminal duct lobular unit?
the basic functional secretory unit of the breast.
in the non-lactating breast, terminal ductules lead into an intralobular collecting duct which leads into the lactiferous duct for that lobe
the lactiferous duct leads to the nipple, passing through an expanded duct region near the nipple termed the lactiferous sinus
identify the different structures of the secretory lobule within the breast?
what type of epithelium is within the secretory lobule?
within the lobule, the secretory epithelial cells line the acini and vary from cuboidal to columnar
the secretory cells of the acinus are surrounded by myoepithelial cells which are contractile epithelial cells which in turn are surrounded by the basal lamina
what is the difference between smaller ducts and larger ducts?
larger ducts, such as a lactiferous duct, are lined by an epithelium that varies from a thin stratified squamous to stratified cuboidal
myoepithelial cells are present
describe the histological structure of the nipple?
the nipple has a wrinkled surface and is covered by a thin, highly pigmented keratinized stratified squamous epithelium
it has a core of dense irregular connective tissue mixed with bundles of smooth muscle
here several lactiferous ducts (LD) can be seen – each will serve one lobe of the breast
identify the types of epithelium within the nipple?
as the duct approaches the surface, it becomes lined by stratified squamous epithelium, however deeper it is lined by stratified cuboidal epithelium (b)
deeper still the duct lining may become only one cell thick
several sebaceous glands (arrows) are present, and in (c) it is clear that these end directly on the surface of the skin. The core of the nipple can be seen at (d), showing the fibrocollagenous tissue mixed with smooth muscle bundles.
descrie the changes which occur in the breast during the menstrual cycle?
during the luteal phase, the epithelial cells increase in height, the lumina of the ducts becomes enlarged and small amount of secretions appear in the ducts
describe the dramatic changes which take place in the breast if pregnancy occurs?
1st trimester - elongation and branching of the smaller ducts, combined with proliferation of the epithelial cells of the glands and myoepithelial cells
2nd trimester - glandular tissue continues to develop with differentiation of secretory alveoli. Also, plasma cells and lymphocytes infiltrate the nearby connective tissue
3rd trimester - secretory alveoli continue to mature, with development of extensive rER
which of the following histological slides is non-lactating and which is lactating
left - non-lactating
right - lactating
identify the different structures within lactating breast?
during pregnancy, oestrogen and progesterone stimulate proliferation of secretory tissue and fibro-fatty tissue becomes sparse
describe the composition of human milk?
88% water
1.5% protein (mainly lactalbumin and casein)
7% carbohydrate (mainly lactose)
3.5% lipid
with small quantities of ions, vitamins and IgA antibodies
describe the different secretory mechanisms by different components of milk?
lipid droplets are secreted surrounded by membrane and carrying a small amount of cytoplasm with it - this form of secretion is known as apocrine secretion.
the proteins in milk are made in the rER, packaged in the Golgi apparatus and secreted via vesicles (v) which merge with the apical membrane to release only their contents into the duct system - this is merocrine secretion (also termed exocytosis).
