histology of breast

1. THE BREAST(MAMMARY
GLAND]
Dr.SHERIN SHAHANA

2. INTRODUCTION
• Highly modified apocrine sweat gland
• Develop embryologically along two lines, the milk lines, extending
from the axillae to the groin.
• The breasts of both sexes follow a similar course of development until
puberty, after which the female breasts develop under the influence
of pituitary, ovarian and other hormones.

3. STRUCTURE OF BREAST
• Each breast consists of 15 to 25
independent units called breast lobes, each
consisting of a compound tubulo-acinar
gland
• Within each lobe of the breast, the main
duct branches repeatedly to form a number
of terminal ducts, each of which leads to a
lobule consisting of multiple acini.
• Each terminal duct and its associated lobule
is called a terminal duct–lobular unit(TDLU)

4. Continues…
• Immediately before opening onto the surface, the duct forms a
dilatation called the Lactiferous sinus.
• The lobules are separated by moderately dense collagenous
interlobular tissue .
• Intralobular tissue is the supporting tissue surrounding the ducts
within each lobule is less collagenous and more vascular.

5. NIPPLE
• Contains bands of smooth muscle, arranged in parallel to the
lactiferous ducts and circularly near the base.
•
• Contraction of this muscle causes erection of the nipple.
• Areola is pigmented area around the nipple and which contains
sebaceous glands which are not associated with hair follicle.

6. BREAST TISSUE FROM A NON PREGNANT
WOMEN IN REPRODUCTIVE AGE
• The branching duct system is
surrounded by relatively dense
fibrous interlobular tissue and
adipose tissue .
• The interlacing (reticular)
arrangement of the coarse collagen of
the interlobular tissue is seen.

7. Continues…..
• The breast ducts and acini are lined
by two layers of cells, a luminal
layer of epithelial cells and a basal
layer of flattened myoepithelial
cells.
• In the larger ducts the luminal
epithelial cells are tall columnar in
type whereas, in the smaller ducts
and acini the epithelial cells are
cuboidal.
• A discontinuous layer of stellate
myoepithelial cells with pale
cytoplasm surrounds the ductal
lining cells.

8. • During the reproductive years, the duct epithelium undergoes mild
cyclical changes under the influence of ovarian hormones.
• Early in the cycle, the duct lumina are not clearly evident but, later in
the cycle, they become more prominent and may contain an
eosinophilic secretion.

9. BREAST DURING PREGNANACY
• Under the influence of progesterone and estrogens terminal duct
epithelium proliferates to form increased numbers of secretory acini.
• Breast proliferation is also dependent on prolactin, human chorionic
somatomammotropin, thyroxine and corticosteroids.

10. Continues……
• In low magnification breast shows enlarged breast lobules separated
by septa of interlobular tissue .
• In higher magnification breast tissue shows dilated acini lined by
cuboid to low columnar epithelial cells with vacuolated cytoplasm.
• The intralobular stroma is less prominent and contains an infiltrate of
lymphocytes, eosinophils and plasma cells
• As pregnancy progresses, the acini begin to secrete a protein-rich
fluid called colostrum, the accumulation of which dilates the acinar
and duct lumina .

12. LACTATING BREAST
• Lactating breast composed of distended acini lined by flattened
epithelium .
• The distended acini are filled with an eosinophilic material containing
clear vacuoles caused by lipid droplets which have dissolved out
during tissue preparation.
• The interlobular tissue now reduced to thin septa between lobule.

14. MALE BREAST
• Composed of ductal structures
only within collagenized stroma,
with no / rare acini

15. MENOPAUSE
• Reduction of estrogen and
progesterone causes involution
and atrophy of TDLUs
• Reduction in size and complexity
of acini, loss of specialized
intralobular stroma
• Hyalinized stroma with relative
increase in fat