MAMMARY GLANDS
STRUCTURE OF MAMMARY GLANDS :
Each breast is a
hemispheric projection of size anterior
to the pectoralis major and serratus anterior muscles and attached to them by a
layer of deep fascia composed of dense irregular connective tissue.
Each breasts has one pigmented projection, the nipple, that
has a series of closely spaced openings of ducts called lactiferous ducts,
where milk emerges. The circular
pigmented area of skin surrounding the nipple is called the areola : it appears rough due to modified sebaceous
(oil) glands contained in it. Strands of connective tissue called the
suspensory ligaments of the breast (cooper’s ligaments) run between the skin and deep fascia and
support the breast.
These ligaments become looser with age or with the excessive
strain that can occur in long term jogging.
Wearing a supportive bra slows the appearance of “Cooper’s droop”.
Within each breast is a mammary gland, a modified sudoriferous
gland that produces milk .
A mammary gland consists of 15-20 lobes, or compartments,
separated by a variable amount of adipose tissue. In each lobe are several
smaller lobules, composed of grapelike clusters of milk secreting glands called
alveoli embedded in connective tissue.
Contraction of myoepithelial cells surrounding the alveoli
helps propel milk toward the nipples.
Milk passes from the alveoli into a series of secondary
tubules and then into the mammary ducts.
Near the nipple , the mammary ducts expand to form sinuses
called lactiferous sinuses, where some milk may be stored before draining into
a lactiferous duct. Each lactiferous duct carries milk from one of the lobes to
the exterior.
FUNCTIONS :
1.
The functions of the mammary glands are the
synthesis,secretion, and ejection of milk. These functions called lactation,
are associated with pregnancy and childbirth.
2.
Milk production is stimulated largely by the
hormone prolactin from the anterior pituitary, with contribution from
progesterone and estrogens.
3.
The ejection of milk is stimulated by oxytocin,
which is released from the posterior pituitary in response to the sucking of an
infant on the mother’s nipple (sucking).
CLINICAL ASPECT :
1.
Female breasts are highly susceptible to cysts
and tumours.
2.
In fibrocystic disease , the most common cause
of breast lumps in females, one or more cysts and thickenings of alveoli
develop. The condition is probably due to relative excess of estrogens or a
deficiency of progesterone in the postovulatory phase of the reproductive
cycle.
3.
Fibrocystic disease usually causes one or both
breasts to become lumpy,swollen, and tender a week or so before mentrutation
begins.
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