Lactogenesis
and
Composition of Breast Milk
I. General Information
A. Embryologically: belong to integument
B. Functionally: part of reproductive
system
C. Modified apocrine sweat glands
II. Anatomy
Position and Attachment
1.
2.
3.
4.
5.
Lateral aspect of pectoral region
Located between ribs 3 and 6/7
Extend form sternum to axilla
Surrounded by superficial fascia
Rest on deep fascia
Breast Anatomy
Structure, continued …
Secretory epithelium
a. Changes with hormonal signals
b. Onset of menstruation
c. Pregnancy (glands begin to
enlarge at 2nd month)
Structure, continued …
Vessels & Nerves
1. Arteries: derived from thoracic
branches
a. Axillary arteries
b. Internal mammary arteries
c. Intercostal arteries
Vessels & Nerves, continued …
Veins
a. form a ring around the base of the
nipple (“circulus venosus”)
b. External mammary v to axillary v
c. Internal mammary v to subclavian v
Breast Anatomy, con’t…
Nerve Innervation: derived from:
a. anterior & lateral cutaneous
nerves of thorax
b. spinal segments T3 – T6
Lymphatics
Subclavian
nodes
Axillary
nodes
Lateral
pectoral
nodes
Parasternal
nodes
Lactation: four stages
•
Mammogenesis
•
Lactogenesis
•
Galactokinesis
•
Galactopoiesis
Mammogenesis

From 24th week of pregnancy

Growth of ducts and lobuloalveolar systems

Hormonal influencesestrogen, adrenal steroids, progesterone,
estrogen, prolactin, adrenal steroids and
growth hormone
Lactogenesis I


Begins during pregnancy
Alveoli distend with colostrum
Lactogenesis II


Initiation of significant milk secretion at or just
after parturition- colostrum
Mature milk secretion begins 30-40 hours
postpartum and averages 1-2 ml/g of breast
tissue /day
Lactogenesis III

Milk supply is more firmly establishedautocrine control system begins

More the milk is removed from the
breasts, more the breast will produce
milk
Galactokinesis




Ejection of Milk
Suction exerted by the baby during
suckling
Contractile mechanism
Draught sensation
Lactation Reflex
Galactopoiesis



Maintenance Of Lactation
Prolactin
Sucking
Composition of Breast Milk (gms/100ml)

Sugar
: 7

Fat
: 3.5

Protein
: 1.2

Minerals : 0.4

Water

Calories : 67
: 89
‘Breast fed infants, are Healthy Infants’
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