GLANDULAR EPITHELIA
BREAST:
We interrupt our survey of the gastrointestinal tract to
consider the duct-and-acinus
architecture of the breast, which will be helpful in
understanding several other tissues. The
acinus is a circlet of cells grouped around a small lumen.
Inconspicuously small, vacuolated
myoepithelial cells rim acini and small ducts to squeeze the
secretions on their way. A small
duct called the terminal duct in the breast is connected to the
lumen. Several acini and their
terminal ducts will drain into a larger duct; this grouping of
acini, terminal ducts and ducts
serving them is a lobule. The relationship of large ducts,
terminal ducts and acini is that of a
tree trunk, branches, and leaves. The lobule is the most easily
appreciated unit structure of
the breast, and it is much more easily seen than the similar
structures in other tissues
because it is embedded in almost transparent fat. Drawing an
imaginary line around the
other limits of a lobule should give a rounded outline, like a
well-pruned tree.
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