Anatomy and hystology of breast
Physiology of the breast
breast or mammary gland (lat. mamma, grc. mastos) is the largest skin gland.
That is modified sweat gland. It
exists in the male as well as in the female, but in the former only in the
rudimentary state (2) (figure 1).
At the end of the first month of embryonic development, the mammary gland begins to develop as a solid bud of epidermis into the underlying mesenchyme (figure 2). This primary bud occurs from cranial part of the mammary ridges, thickened strips of ectoderm. Each primary bud give rise to several secondary buds that develop into the lactiferous ducts and their branches that make up the mammary gland.
During pregnancy that the breast assumes its complete morphologic maturation and functional activity (figure 4 and figure 5).
ANATOMY AND HISTOLOGY OF BREAST
is a symmetric double organ. It
reaches normal size between 16 to 19 years (figure 4). It is situated toward the
lateral aspect of pectoral region, corresponding to the interval between the
second and the seventh rib and extending from lateral side of the sternum to the
axilla (8, 9). Radix of breast (radix mammae) is situated under second rib,
extending into body (corpus mammae). Breast
is covered by skin that in the lower part makes sharp flexure like a groove
(sulcus submammalis) and becomes skin of pectoral region (figure
6) (8, 9).
the top of the breast is a small conical prominence, the nipple (papilla mamme).
The nipple is surrounded by an areola, pigmented area (figure
6) (8, 9).
breast is consisted of gland- tissue that is embedded into connective tissue and
padded with fat tissue (figure 7). The
gland tissue is divided into 10 to 20 sections called lobes and is composed of
lobules connected together by connective tissue (figure 8 and
Lobules are structured as a small milk- producing gland.
This structure is responsible that
during palpation of the gland tissue feels granular formation.
Each lobe has its own draining duct.
They converge toward the areola, beneath which form dilatation (sinus
lactiferus), and again become contracted and narrow before opening at the
nipple. Lobes and its ducts are
radial lined around nipple, therefore each section should be radial toward
supplying the breast are derived from lateral thoracic artery, internal thoracic
artery and intercostal arteries. Internal
thoracic arteries and its perforating branches supply a medial part of the
breast. Lateral thoracic artery
supplies a lateral part of the breast. Profound
part is supplied by intercostal arteries and theirs branches (8).
The veins describe
an anastomotic circle round the base of the nipple, called by Haller circulus
venosus. From this, large branches
transmit the blood from medial part of the breast into internal thoracic veins
and from the lateral part of the breast into lateral thoracic vein and
intercostal veins (figure 10) (8).
The lymph vessels of the breast are situated into two layers (superficial and profound layers), making networks that are
interconnected. Superficial lymph
vessels transmit the lymph fluid into axillary lymph nodes.
It is important to mention that some of the superficial lymph vessels
transmit the fluid into axillary lymph nodes from the other side of the body,
directly or indirectly using the lymph vessels from the other side.
The lymph fluid from region of nipple, areola and lateral part of the
breast is transmitted into axillary lymph nodes along inferior margin of the
pectoral major muscle. From the
lateral part, lymph fluid is firstly transmitted to the intercostal lymph nodes
and then to the axillary lymph nodes. From the superior and profound parts lymph
vessels run along the fascia of the pectoral major muscle to the axillary
region. Some part of those vessels
perforate that muscle and run to the inrfa and supraclavicular lymph nodes.
From the medial, inner part of the breast lymph vessels perforate the
intercostal spaces and empty themselves into parasternal lymph nodes.
These are the only lymph vessels that pass by axillary lymph nodes (8).
lymph nodes, there are 30 to 40 of them. They
are divided into few groups: apical lymph nodes, central lymph nodes, lateral
lymph nodes, pectoral lymph nodes and subscapular lymph nodes (figure
nerves innervate the breast.
Branches of the supraclavicular nerves also innervate superior part of
the breast (8).
The breasts are accessory glands of the generative
systems. They exist in the male but only in the rudimentary state.
Breasts secrete the milk enabling nutrition of the infant by hormonal
feedback (1, 8).
In the female, estrogens cyclically stimulate
growth of the breast. But, complete
development of the breast occurs during the pregnancy.
the pregnancy, placenta secretes large amount of estrogen that induces the
growth, division, elongation of the tubular duct system, nipple maturation and
fat deposit. Besides estrogen, at
least four hormones have influence, permissive role in the control of milk
formation: thyroxin, insulin, growth hormone and glucocoriticoids of the
under the influence of progesterone, lobules are increased, alveoli bud and
alveolar cells get secretory characteristics.
Estrogen and progesterone also have a specific inhibitory effect on the
produced by pituitary gland, plays
the critical role in the initiation and maintenance of lactation in the
puerperium. Its concentration rises during
pregnancy and at the end of pregnancy is 10 times higher than normal.
Furthermore, placenta produces large amount of the
somatotropin that prepares the breast for milk production.
Until delivery, breasts produce small amount of
colostrum that does not contain fat unlike regular milk.
After delivery, production of estrogen and progesterone decreases
allowing lactogen effect of prolactin to be expressed.
Therefore, two or three days after delivery breasts start to produce high
amount of milk. Except prolactin,
other hormones such as insulin, growth hormone and glucocoriticoids have an
important role in the milk secretion due to their role in metabolisms of the
amino acid, glucose, fat acid and calcium, which are needed for milk generation
level of the prolactin decreases after delivery on the regular level, but
prolactin secretion is enhanced by stimulation of the breasts, such as the act
of nursing (each nursing cause 10 times fold increment secretion of the
prolactin that lasts for one hour). That
prolactin provides milk for a next nurse. If
a woman does not nurse or empty her breasts postpartum or hypothalamus or
pituitary gland are impaired, lactation usually ceases in 1 to 2 weeks.
Milk is continuously secreted into alveoli of the
breast. Oxytocin causes contraction of the myoepithelial cells of the
mammary alveoli, causing them to expel milk from the secretory tissue to the
is secreted at the same time with the prolactin, with the transmission of
impulse along somatic nerves through spine to the hypothalamus. This process
starts one minute after infant starts to suck.
Sometimes, even infant’s cry can induce oxytocin secretion.
Inhibition of secretion of the oxytocin is possible as a result of the
psychogenic factors or generalized sympathetic
stimulation. Therefore, woman
should have undisturbed puerperium to nurse (12, 15).
the male, the breast is a rudimentary organ, relatively insensitive to endocrine
influences. On the other hand, in
the female, the more complex breast structure and the extreme sensitivity to
endocrine influences predispose this organ to a number of pathologic conditions.
breast diseases can be divided into two groups: non-tumor and tumor disease.
disorders: amastia (lack of breast), micromastia (little breast), macromastia
(big breast), polymasita (extra breasts), athelia (nipple deficiency),
microthelia (small nipple), polythelia (extra nipple).
(nonpuerperal or inappropriate lactation),
bleeding breast, mastodinija (aching breast), extended period of the
breast feeding, excessive milk production, small milk production and spontaneous
leakage of the milk.
atrophy (“shrivelled” breasts), dystrophy (transformation of breast tissue
to fat, mucine or calcified formation) fat necrosis (focal necrosis of fat
tissues in the breast)
changes: theilitis (nipple inflammation), areolitis (areola inflammation),
intertrigo (eczema of the submammal sulkus), mastitis (inflammation of the milk
gland, usually happens in the first two weeks after the delivery), apses
(localized purulent inflammation), carbuncle (purulent skin and subcutaneous
infections of the breast) and rarely tuberculosis, syphilis and actinomycosis.
most ordinary and the most important is fibrocystic
disease of the breast. That is the most common breast alteration at all and the most
common reason of coming to the physician. It
is also stated as predisposed factor of the breast cancer.
It is characterized by connective tissue proliferation (fibrosis) or milk
gland cells proliferation (epithelial hyperplasia) or/and the formation of
cysts (figure 13). These changes
are caused by the hormonal effects (estrogen, progesterone, prolactin) (16,17).
Benign tumors. The
most common is fibroadenoma (it is more common in younger female population) and
(in the ducts which often causes bleeding, so even 50% of all bleeding discharge from the nipple is caused by that change). The others are rather rare. Those are: lipoma, haemangioma, neurinoma, chondroma. Cysts also belong to this group. The special type of rare breast tumor is phyllodes tumors (consisted of cystic formations, giving the gross leaf-like pattern) (4).
Malign tumors (breast cancer). For
this topic, see chapter.