Anatomy lactation

1. ELIZABETH CHODZAZA
MELANIE HAMI
BARBARA MLEWA
2010

2. Learning outcomes
 Describe the gross and microscopic structure of the
breast.
 Explain the physiology of lactation
 Explain factors essential for maintenance of lactation

3. THE BREAST
 The breasts are also known as mammary glands
and they are glandular tissues stimulated by
increase in female hormones at puberty, during
pregnancy and lactation period.
 They are regarded as accessory glands of the
female reproductive system.

4. SITUATION
 One breast is situated on each side of the sternum and
extends from the level of the second to the sixth rib.
 They lie in superficial fascia of the chest wall over the
pectoralis major muscle
 Held in position by suspensory ligaments of cooper
SHAPE
 Hemispherical
 Has a tail of tissue extending towards the axilla-TAIL
OF SPENCER

5. SIZE
 Varies with different individuals and with the stage of
development and age.
 The external shape or size of the breast is not predictive of its
internal anatomy nor of its lactation potential.
 GROSS STRUCTURE OF THE BREAST
 Skin: the breast is covered with skin and subcutaneous
tissue, at the centre around the nipple the covering
consist of primary areola which is specialized form of
skin.
 Axillary tail: a tissue extending towards the axilla

6. GROSS STRUCTURE OF BREAST CT
 Areola: a circullar of loose pigmented skin about
2.5 cm in diameter
:found at the centre of each breast
:pale pink in fair skinned women and darker
in dark women
:colour deepens with pregnancy
:approx. 20 sebaceous glands within each areola
 Nipple: lies in the centre of the areola
: its at the level of 4th rib
: about 6mm in length
:composed of pigmented erectile tissue

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9. GROSS STRUCTURE OF BREAST CT
:highly sensitive-has nerve endings
:surface of nipple is perforated by small orifices
-openings of lactiferous ducts
MICROSCOPIC STRUCTURE OF BREAST
 Largely composed of glandular and fatty tissue covered
with skin
 Glandular tissue: is divided into 15 to 20 lobes in each
breast completely separated by bands of fibrous tissue
 Each lobe is made up of 40 tiny lobules which are
connected together to form ducts by loose connective
tissues and blood vessels

10. MICROSCOPIC STRUCTURES OF BREAST CT
 Internal structure resemble half grapefruit or orange
 Each lobe is a separate functional unit composed of:
 Alveoli:
 Lactiferous tubes:
 Ampulla:
 Continuation of lactiferous ducts:

11.  Each lobule consist of a
rounded cluster of between 10
and 100 specialised alveoli
called acini cells which are
secretory units of the glands
 The alveoli have epithelial
cells which manufacture
colostrum during pregnancy
up to 3rd day postpartum
 The alveoli open up to tiny
ducts which unite to form
larger ducts known as
lactiferous ducts

13. MICROSCOPIC STRUCTURE OF BREAST
 Fibrous tissue: fascia of which the breast rest and send
out extensions in the form of fibrous processes called
suspensory ligaments of cooper; from the back of
the breast forwards to the subcutaneous tissue
underlying the skin and nipple. This supports the
breast.

14.  Breast profile:
 A ducts
 B lobules
 C dilated section of duct
to hold milk
 D nipple
 E fat
 F pectoralis major muscle
 G chest wall/rib cage
Enlargement:
 A normal duct cells
 B basement membrane
 C lumen (center of duct)

15. MICROSCOPIC STRUCTURE OF BREAST
 Alveoli: hollow cavities, a few millimeters large) lined
with milk-secreting cuboidal cells (acini cells) and
surrounded by myoepithelial cells. These alveoli join
up to form groups known as lobules. The myoepithelial
cells can contract under the stimulation of oxytocin
thereby excreting the milk from glands through the
lactiferous ducts toward the nipple,
BLOOD SUPPLY
 Internal and external mammary artery, upper
intercostal arteries
 Venous drainage by corresponding vessels into the
internal mammary and axillary veins

16. LYMPHATIC DRAINAGE
 Into axillary glands, mediastinum nodes and portal
fissure of the liver
 Lymphatic vessels of the two breast communicate with
each other
NERVE SUPPLY
 Functions of the breast are controlled by hormones
 Skin is supplied by branches of thoracic nerve and
sympathetic nerves around the areola and nipple
FUNCTION
 Supplying milk for the infant
 Sexual organ

17. PHYSIOLOGY OF LACTATION
 During pregnancy several hormones develop the breast
and stimulate secretion of colostrum
 Oestrogen, Progesterone and Prolactin (production is
associates with neonatal feeding with high levels produced
during night feeds).
 Physiology of lactation: Hormonal control
:Production of milk
:Flow of milk: Back pressure
:neuro-hormonal
reflex(let down)

18. HORMONAL CONTROL
 Separation and expulsion of placenta leads to
reduction in circulation of oestrogen and progestrone
resulting in release of prolactin by anterior pituitary
gland
 Oestrogen suppresses action of prolactin-promotes
production of milk 3 days after delivery after allowing
adequate amounts of circulating prolactin
 Prolactin acts on the acini-milk producing cells
 Thus if suppression of milk is required oestrogen can
be administered eg stilboestrol

19. MILK PRODUCTION
 Increased blood supply to the breasts brings important
nutrients for milk production
 Milk is formed as small fatty globules within the
cytoplasm of the secreting cells of the alveoli.
 Globules arise in the bases of these cells and gradually
unite to form small droplets
 As new globules are produced the droplets are pushed
towards the surface of the cell until they burst
 Through cell membranes they enter the lactiferous
tubule accompanied by a little cytoplasm of the cell
substance.

20. MILK PRODUCTION CT
 They join with droplets from other cells and the
terminal portions of the tubules within the excreting
alveoli become filled with milk
 Milk is formed from a volume of blood about 350 times
greater than that of the milk produced
 Composition of milk is dependent on the metabolism
of the alveolar cells which make the nutrients from
amino acids and glucose(lactose)
 Mother’s diet does not affect composition of milk
except if she takes large quantities of vitamins and fats

21. FLOW OF MILK
Two factors are involved in the passage of milk from
secretory cells to the nipple:
a) BACK PRESSURE
 Force of new globules forming in the cells pushes the
foremost ones into the lactiferous tubules to
lactiferous duct and stored in the ampullae
b) NEURO-HORMONAL REFLEX (let down reflex)
 Rhythmic sucking movements empties the ampullae
 Large lactiferous ducts cause myo-epithelial cells
surrounding alveoli and smaller ducts to contract
and force more milk towards the nipple.

22. FLOW OF MILK CT
 Stimulus on the sensitive nipple, crying of baby or just
the thought of the baby-reaches the hypothalamus by
nervous reflex-oxytocin is released from posterior lobe
of pituitary gland.
 Oxytocin stimulates myo-epithelial cells of the breasts
and nipples to contract causing more-sensation felt in
both breasts refered to as ‘draught’
 Oxytocin also stimulates the uterus to contract causing
pain while breastfeeding-promoting involution of
uterus
 Let down reflex can be inhibited by pain, fear or
embarrassment. Therefore ensure pain free during BF

23. MILK WITHDRAWAL
A vacuum is created in the babys
mouth which helps draw more milk
from the lactiferous sinuses.
As milk is drawn from the sinuses and
the lower ducts more milk flow down
from the upper lactiferous ducts,
tubules and alveoli to take its place.
This continues until the breast is
emptied

24. MILK WITHDRAWAL
 The neonate grasps the whole nipple and the primary
areola are drawn into the babys mouth
 The neonate closes its jaws onto the areola tissue
situated over the lactiferous sinuses.
 This expresses milk from the sinuses into the baby’s
mouth who then swallows.

25. MECHANISM OF CONTROLLING LACTATION AND MILK EJECTION
 The pyramid below illustrates how lactation is
controlled and ejected.
 Follow the numbers from top to left side and top to
right side.

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29. THANK YOU