PHYSIOLOGY OF LACTATION

PHYSIOLOGY OF LACTATION

1. DR NILESH KATE
MBBS,MD
PROFESSOR
DEPT. OF PHYSIOLOGY
PHYSIOLOGY
OF LACTATION.

2. OBJECTIVES.
Development & functional anatomy of breast
Physiology of lactation.

3. INTRODUCTION.
Breastfeeding characteristics of all mammals
including humans
Method of nourishing newborn.
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4. Development of Breast.
Present in both the sexes but rudimentary in
males & well developed in females.
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5. Phases of development of
breast.
In intrauterine life
At birth
At puberty
In pregnancy
During lactation
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6. Breast in intrauterine life
(Embryogenesis)
Mammary bud – at 18-19
weeks of gestation
thickened mass of
epithelium develop.
16-20 solid outgrowths
arises & project into dermis
Then this thickened mass &
outgrowth canalized – form
Rudimentary duct system.
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7. Breast in intrauterine life
(Embryogenesis)
Terminal part of outgrowth
proliferate into secretory
elements, Occurs at puberty.
Proximal end of each duct
opens into common pit by
cavitation of thickened
mass
Growth of mesodermal
tissue pushes wall of the pit
outwards as Nipple.
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8. Breast at birth
At birth rudimentary as tiny nipples & few
ducts radiating from it.
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9. Breast at puberty
Upto puberty remain quiescent then changes
occurs
Thelarche – (9-11 yrs of age) at the time of
puberty before menses.
Breast gets enlarged & only duct system proliferate
& shows branching.
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10. Breast at puberty
At Menarche – after menses cyclical growth
correspond with menstrual cycle.
In proliferative phase – duct cells proliferate.
In luteal phase – progesterone stimulate
proliferation of terminal ductules – glandular
tissue forms.
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11. Breast at puberty
At Menstruation –as both oestrogen &
progesterone levels no prolifearation of
duct cells & glandular tissue.
With further cycles progressive growth
occurs with fat deposition in adipose tissue.
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12. Breast in pregnancy
Growth of both – Glandular & Ductal tissue
occurs.
Only during first pregnancy glandular tissue
develops fully.
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13. Breast in pregnancy
In first half – Duct system proliferate &
shows sprouting & branching along with
growth of stroma & deposition of fat.
In second half – growth of glandular tissue
occurs.
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14. Breast during lactation
After child birth alveolar cells get enlarged &
distended & starts forming milk
(Lactogenesis)
Involution – after normal period of lactation
(7-9 months) alveolar epithelium undergoes
apoptosis & glands revert back to non-
pregnant state.
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15. Functional anatomy of breast.
Gross anatomy –
round elevated
structure present over
pectoral region, with
central dark
pigmented area
-areola & projected
above surface -
Nipple.
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16. Histological structure.
The fascia covering mammary gland is
connected by suspensory ligaments to
overlying skin & underlying muscle.
Consists of 15-20 lobes & each lobe has
number of lobules.
Glandular tissue – consists of alveoli having
secretary cells
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17. Histological structure.
Secretion – Apocrine in nature by exocytosis
into ducts.
About 15-20 ducts opens at summit of nipple
Just before opening lactiferous ducts shows
dilatation called – Lactiferous sinus.
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18. Histological structure.
Smaller ductules lined by single columnar
epithelial cells & near opening at nipple lined
by squmous cells.
Around alveoli ductules & lobules are
present in myoepithelial cells – so squeeze &
pour content into ductules.
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19. Electron microscopically.
Secretory cells contains rough & smooth
endoplasmic reticulum, numerous
mitochondria, Golgi apparatus & Lysosomes.
Protein as membrane bound vesicles & fat as
large globule.
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20. Control of breast development
and growth
Oestrogen – mainly for ductal growth & fat deposition,
also causes thickening of nipple.
Progesterone – for Glandular tissue development.
Other hormones – Growth hormone, thyroxine, cortisol &
insulin cause growth & development.
Corpus luteal & placental hormones – during pregnancy
Prolactin.
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22. HUMAN PROLACTIN
Structure &
secretion
Single peptide chain
secreted by
acidophilic cells of
anterior pituitary
gland.
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23. Placental concentration
Pulsatile
Shows diurnal variations
During pregnancy – start at 8
th
week & peak
(200-400 ng/ml) at term
Sources – placenta, amniotic fluid & maternal
anterior pituitary gland.
During pregnancy & lactation – affected by
oestrogen.
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24. Control of prolactin secretion
Hypothalamic
control – Prolactin
inhibitory factor from
Arcuate nucleus of
hypothalamus acts on
anterior pituitary
gland.
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25. Factors enhancing release of
Prolactin.
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26. PHYSIOLOGICAL EFFECTS OF
PROLACTIN
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27. Applied aspects.
Chiari-Frommel syndrome. –
Persistence of lactation (Galactorrhoea)
Amennorrhoea
Genital atrophy ( Due to suppression of FSH & LH)
Chromophobe cell tumour of pituitary
gland.
Galactorrhoea & high level prolactin in non-
pregnant womens.
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28. PHYSIOLOGY OF LACTATION.
Phases of lactation
Mammogenesis
Lactogenesis
Galactokinesis
Galactopoiesis.
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29. Mammogenesis
Breast develops fully
& prepared for milk
secretion after
delivery.
Hyperplasia of ductal
& alveolar tissue
Areola – Pigmented.
Sebaceous glands
becomes prominent in
areola
Nipples become larger
& pigmented.
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30. Lactogenesis
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31. Human milk
Types
Colostrum – Deep yellow colour fluid during
postpartum
Contains – high protein, immunoglobulins & lactoferrins
Granular bodies – colostrum corpuscle (alveolar cells,
Leucocytes with fats)
Transition milk or intermediate milk – 6-15
th

day.
Mature milk – after 15
th
day.
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32. Composition of human milk.
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33. Formation of milk.
Mammary gland – metabolically active
Amino acids , FA, glucose & Ca derived from
plasma into alveolar cells
Process involved are
Fat synthesis & secretion
Ion & water secretion
Transcytosis of immunoglobulins
Exocytosis.
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34. Galactokinesis
expulsion of milk
Milk ejection
Milk expulsion
Milk let down
Suckling effect.
(Psychological
component)
Cry, sight, sound.
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35. Inhibition of milk ejection
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36. Galactopoiesis
Maintenance of milk secretion.
Depend on surge in prolactin secretion.
In nursing mothers reflex causes 10-20 fold
rise in prolactin secretion for 1 hr & it occurs
at every feeding.
It depend on infants demand.
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37. Importance of lactation.
Advantages of breastfeeding to the baby
Advantages of breastfeeding to the
mother.
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38. Advantages of breastfeeding to
the baby
Balanced diet – contains proteins, minerals, fats,
carbohydrates & vitamins
Protection against infection – high lymphocytes,
neutrophils, macrophages, lysozymes &
immunoglobulins.
Easily digestible
Growth factors – epidermal growth factors, insulin
& somatostatin C
Other – sterile, convenient, inexpensive, no allergy.
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39. Advantages of breastfeeding to
the mother.
Lactational ammenorrhoea (natural
contraception)
Involution of uterus.
Protection against breast engorgement.
Protection against obesity – body fat used for
milk synthesis.
Emotional bonding.
Protection against cancer.
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