This document discusses the anatomy and physiology of lactation. It describes the parts of the female breast including lobes, glandular tissue, milk ducts, nipples, areolae, blood vessels, and nerves. It explains the processes of mammogenesis during pregnancy, lactogenesis after delivery as milk production begins, and galactopoiesis which is the maintenance of milk production through regular removal of milk from suckling. Key hormones involved are prolactin, estrogen, progesterone, and oxytocin which works through the milk ejection reflex.

1. P R E P A R E D B Y :
J Y O T I R A N A B H A T
MANAGEMENT OF
LACTATION

2. Anatomy of breast

3. Anatomy of breast

4. CONTD..
 There are many different parts to female breast
anatomy, including:
 Lobes: Each breast has between 15 to 20 lobes or
sections. These lobes surround the nipple like spokes
on a wheel.
 Glandular tissue (lobules): These small sections
of tissue found inside lobes have tiny bulblike glands
at the end that produce milk.
 Milk (mammary) ducts: These small tubes, or
ducts, carry milk from glandular tissue (lobules) to
nipples.

5. CONTD..
 Nipples: The nipple is in the center of the areola.
Each nipple has about nine milk ducts, as well as
nerves.
 Areolae: The areola is the circular dark-colored
area of skin surrounding the nipple. Areolae have
glands called Montgomery’s glands that secrete a
lubricating oil. This oil protects the nipple and skin
from chafing during breastfeeding.
 Blood vessels: Blood vessels circulate blood
throughout the breasts, chest and body.

6. CONTD..
 Lymph vessels: Part of the lymphatic system, these
vessels transport lymph, a fluid that helps your
body’s immune system fight infection. Lymph vessels
connect to lymph nodes, or glands, found under the
armpits, in the chest and other places.
 Nerves: Nipples have hundreds of nerve endings,
which makes them extremely sensitive to touch and
arousal.

7. PHYSIOLOGY OF LACTATION
 Breastfeeding and breastmilk must be considered in
the context of maternal physiology and infant
development rather than just the narrow role of
optimizing infant nutrition. The lactating breast has
a high metabolic activity.

8. PHYSIOLOGY OF LACTATION contd…
 Successful lactation requires the development of
fully functional mammary glands. Whereas other
major organs are morphologically and functionally
relatively mature at birth, the mammary gland
undergoes very limited structural development in
utero, with the most dramatic changes in women
occurring during puberty, pregnancy, lactation, and
weaning.

9. 1.Mammogenesis
 Mammogenesis is the process of growth and
development of the mammary gland in preparation
for milk production. This process begins when the
mammary gland is exposed to estrogen at puberty
and is completed during the third trimester of
pregnancy.

10. CONTD..
 The mammary gland develops the histologic and
biochemical capacity to synthesize and secrete milk
during pregnancy. Histologic studies have separated
mammary development during pregnancy into two
distinct phases: mammogenesis and lactogenesis 1.

11. CONTD..
 Mammogenesis occurs from early pregnancy and is
characterized by proliferation of the distal elements
of the ductal tree, creating multiple alveoli (acini) of
variable size and shape .
 Lactogenesis 1 occurs in the later stages of pregnancy
and is characterized by the differentiation of resting
mammary cells into lactocytes, with the potential to
secrete the unique fats, carbohydrates, and proteins
characteristic of milk

12. CONTD..
 Initially, mammary development during
pregnancy appears to be an acceleration of the
parenchymal hypertrophy associated with the
menstrual cycle.
 Indeed, an increase in the sensitivity and
tenderness of the breast, and nipple sensitivity in
particular, is often one of the first indications of
pregnancy, and this can occur within a few days of
conception and before the due date of the next
menstrual period.

13. CONTD..
 Thus, the factors initiating mammogenesis at this
time must be closely related to those responsible
for the mother’s recognition of her pregnancy.
Subsequently, the subcutaneous veins become
enlarged and visible through the skin, and the
areola usually enlarges and becomes more darkly
pigmented.
 Extensive lobulo-alveolar growth occurs during
the first half of pregnancy, and in the third
trimester there is a further increase in lobular size
associated with hypertrophy of the lactocytes and
the accumulation of secretion in the lumina of the
alveoli .

15. 2. LACTOGENESIS
 The pituitary hormone prolactin is instrumental in
the establishment and maintenance of breast milk
supply. It also is important for the mobilization of
maternal micronutrients for breast milk.
 Near the fifth week of pregnancy, the level of
circulating prolactin begins to increase, eventually
rising to approximately 10–20 times the pre-
pregnancy concentration. We noted earlier that,
during pregnancy, prolactin and other hormones
prepare the breasts anatomically for the secretion of
milk.

16.  The level of prolactin plateaus in late pregnancy, at
a level high enough to initiate milk production.
However, estrogen, progesterone, and other
placental hormones inhibit prolactin-mediated
milk synthesis during pregnancy. It is not until the
placenta is expelled that this inhibition is lifted and
milk production commences.

17. CONTD..
 The mammary epithelium remains a presecretory
tissue until the abrupt diminution in plasma
estrogen and progesterone concentration that occurs
at the time of delivery. Without the inhibitory
influence of progesterone on mammary epithelium,
prolactin and the other hormones active in the
initiation of milk production can exert their effects
on acinar cells.

18. CONTD..
 By 4–5 days postpartum, estrogen and
progesterone concentrations in the plasma are less
than normal follicular phase levels and the
transition in the acinar epithelium from a
presecretory to a secretory state is complete.
 The initiation of milk production (lactogenesis)
requires 2–5 days in the human being. This is the
length of time necessary for complete secretory
maturation of acinar epithelium.

19. CONTD..
 The inhibition of lactogenesis before delivery
appears to be a consequence of high circulating
levels of progesterone, which competitively inhibits
the binding of cortisol to an intracellular receptor.
 The only other specific hormone required for
lactogenesis is oxytocin.

20. 3. GALACTOKINESIS
Milk let down reflex
 After childbirth, the baseline prolactin level
drops sharply, but it is restored for a 1-hour
spike during each feeding to stimulate the
production of milk for the next feeding.
With each prolactin spike, estrogen and
progesterone also increase slightly.
 When the infant suckles, sensory nerve
fibers in the areola trigger a neuroendocrine
reflex that results in milk secretion from
lactocytes into the alveoli.

21. Contd…
 The posterior pituitary releases oxytocin, which
stimulates myoepithelial cells to squeeze milk
from the alveoli so it can drain into the lactiferous
ducts, collect in the lactiferous sinuses, and
discharge through the nipple pores. It takes less
than 1 minute from the time when an infant begins
suckling (the latent period) until milk is secreted
(the let-down).

22. Oxytocin “milk ejection” reflex

23. `
Figure 28.6.1 – Let-Down Reflex: A positive feedback loop
ensures continued milk production as long as the infant
continues to breastfeed.

24. 4.GALACTOPOIESIS
 Galactopoiesis is the maintenance of milk production
once it has been established by completion of
lactogenesis.
 The single most important factor in successful
galactopoiesis is regular and frequent milk removal
from the mammary gland.

27. CONTD..
Milk removal stimulates further milk
secretion by at least three mechanisms.
First, regular suckling promotes the regular
synthesis and release of both prolactin and
oxytocin, which are necessary for continued milk
secretion.

28. CONTD..
 Second, the breast has the capacity to store milk
for a maximum of 48 hours before there is a
substantial decrease in production.
 This reduced milk production is caused by the
diminished stimulation of the glandular
epithelium by prolactin and the vascular stasis
caused by increased intramammary pressure
resulting from distention of the mammary ducts
and alveoli with stored milk

29. CONTD..
 Blood flow to the mammary glands is significantly
reduced by this increased intramammary pressure,
which diminishes the nutrient and hormonal supply
necessary for milk production.

30. CONTD..
Third, the amount of milk produced daily is fairly
closely related to the demand (i.e. the amount of milk
removed the previous day), as long as the nutritional
and hormonal requirements are met.
Normal levels of prolactin (5–20 ng/ml), with surges
of prolactin and oxytocin at the time of suckling, are
also necessary for the maintenance of normal milk
production.