8. The post-partum period

Question 1

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Answer 1

Question 2

which type of gland is present in the breast - describe their structure

Answer 2

• Mammary glands = modified apocrine sweat glands
• Series of ducts and secretory lobules encased in network of myoepithelial cells
• Each lobule consists of multiple alveoli and is drained by a single lactiferous duct that converge at the nipple

Question 3

which fibrous structures support the breast

Answer 3

Suspensory ligaments of breast (Cooper’s) - condensation of fibrous stroma

1. attach and secure breast to dermis and underlying pectoral fascia
2. separate secretory lobules of breast

Question 4

describe the vasculature of the breast

Answer 4

1. arterial supply:
   - internal mammary aa. (from internal thoracic a.) - predominant suuply
   - external mammary aa. (lateral thoracic and thoracoacromial) and posterior intercostal aa. - accessory blood supply
2. venous drainage: corresponding vv. which drain into axillary and internal thoracic vv.

Question 5

describe the lymphatic drainage of the breast

Answer 5

• breast tissue: axillary nodes (75%), parasternal nodes (20%) and posterior intercostal nodes (5%)
• skin: axillary, inferior deep cervical and infraclavicular nodes
• nipple and areola: subareolar lymphatic plexus

Question 6

describe the innervation of the breast

Answer 6

4th-6th intercostal nn. (anterior and lateral cutaneous branches)

Question 7

describe breast development throughout life, inc. hormonal regulation

Answer 7

1. breast buds appear in both sexes in 6th-9th month foetal life
2. puberty: female breast buds develop under influence of OESTROGEN and PROGESTERONE
3. 1st pregnancy: final maturation - hypertrophy of mammary glands which branch out and expand in resp. to PROGESTERONE and PROLACTIN. Mid-gestation: alveolar cells differentiate to be capable of milk production
4. menopause: breast regression

Question 8

what prevents milk production during gestation and how is production initiated following delivery

Answer 8

• high progesterone:oestrogen ratio during pregnancy prevent alveoli responding to prolactin
• delivery of placenta removes source of large amount of circulating steroids, esp. progesterone

Question 9

describe the hormonal control of milk production

Answer 9

1. suckling stimulates nipple mechanoRs… impulses pass up to brainstem and hypothalamus
2. decreased release of prolactin-inhibiting hormone (PIH, i.e. domapine) and increased release of vasoactive intestinal protein (VIP)
3. VIP increases PROLACTIN release from anterior pituitary
4. prolactin stimulates mammary glands to produce milk

Question 10

describe the milk let-down reflex

Answer 10

1. suckling stimulates nipple mechanoRs… impulses pass up to brainstem and hypothalamus (paraventricular and supraoptic nuclei)
2. increased OXYTOCIN release from posterior pituitary
3. oxytocin stimulates alveolar myoepithelial cells… contract to squeeze milk out of breast

Question 11

describe the mechanisms to produce cessation of lactation

Answer 11

Maintenance of milk production is dependent on sufficient suckling stimulation at each feed to maintain prolactin secretion and remove accumulated milk

If suckling stops, milk production gradually ceases due to:

• low prolactin levels
• turgor-induced damage to secretory cells