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Anatomy of the Breast
The human breast is a paired mammary (milk producing) gland which
appears as a minute swelling in the six-week old fetus. Male and
female babies are born with two rudimentary breasts, and at this
stage there is actually no difference in the size and shape. Both
sexes have an elementary internal system of large milk ducts, linked
externally to two nipples, each surrounded by a small, darker
coloured area, called the areola.
It is only at puberty that the difference between sexes becomes
apparent - a difference controlled by specific hormones. At puberty,
usually some time between the ages of 11 and 14 a girl starts
secreting oestrogen and progesterone - hormones that control sexual
development and fertility. Her breasts begin to swell, with her
nipples becoming more pronounced, and small bumps (sebaceous glands)
appearing on the areola. This onset of breast development is called
the thelarche.
Internally the milk ducts (alveolar ducts) start branching out into
smaller ducts which end in tiny milk-producing glands. The milk
glands are clustered in lobes embedded in fatty tissue and linked to
the ducts which come together like the spokes of a wheel on to a
central reservoir just behind the areola. This is the area where
milk collects when a woman is breastfeeding.
During adolescence the lobes (alveolar glands) and ducts (alveolar
ducts)continue to grow. Fat and connective tissue accumulate around
them, giving the young adult female breast its characteristically
spherical firm shape. Containing no muscle, breast tissue is
attached to the chest wall and overlying skin by fine strands of
fibrous tissue, known as Cooper's ligaments.
Every month, during the reproductive years, hormones stimulate
breast tissue into preparing for pregnancy and lactation, this often
resulting in enlargement and tenderness. This tenderness in its
severe form is called mastalgia. With the onset of the next period
this tenderness disappears with the breasts returning to their
normal state. If pregnancy does occur, ongoing hormonal stimulation
causes further glandular tissue to develop and milk production to
occur.
For many, changes to the breasts are one of the first clues that
conception has taken place. The fullness, tenderness and tingling
sensation persist and, together with a missed period, strongly
suggest pregnancy. This would mark the start of continued growth
throughout pregnancy - increasing as much as three bra cup sizes.
The skin surrounding the nipple will darken and the nipples will
become more prominent, in preparation for breastfeeding.
Final breast size depends largely on inherited genes - just like
height, hair and eye colour, and will only reach their full size and
shape at the end of puberty, at about the age of 20. How large or
small the breasts will be would also depend on how much fatty tissue
is present, while the shape and firmness are determined by the
connective tissue. Each breast is surrounded by lymph glands/nodes
which have three functions: they produce lymphocytes (a type of
white blood cell); they act as filters, removing bacteria and other
particles, such as minute bits of dead tissue; and they produce
antibodies against specific infections - preventing the spread of
disease from the breast into the rest of the body. These specific
masses of spongy tissue are situated in each armpit (axilla), above
the collar bone and behind the central breast bone.
As a woman approaches the menopause her breasts will change in shape
and texture. This is a result of the tissue becoming less compact
and the ligaments losing their elasticity. Further into old age, the
breasts shrink, becoming smaller, or often taking on a pendulous
shape if they were once large.
The breast has been, and probably always will be, a symbol of
femininity, and although all these changes are normal, many women do
experience an adverse reaction to some of the changes at some stage
in their life. Whatever the problem, do not ignore it - you may be
saving your life!
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