Breast Anatomy & Milk Production

Question 1

Define: montgomery tubercles

Answer 1

Located around the areola, contain ductal openings of sebaceous and lactiferous glands and sweat glands

Question 2

Define: alveoli

Answer 2

Milk producing units of the breast

Question 3

Define: lactocytes

Answer 3

Specialized epithelial cells that line the interior of the alveolus. They absorb nutrients, immunoglobulins and hormones from the bloodstream to compose milk.

Question 4

Define: Lobes

Answer 4

clusters of lobules that are filled with alveoli. The breast contains 4-15 lobes can carry milk (through ductules from alveoli to nipple)

Question 5

Breast innervation derives mainly from which nerve?

Answer 5

4th intercostal nerve

Question 6

What reflex may be negatively impacted by severing of the 4th intercostal nerve (such as during breast surgery)

Answer 6

Milk ejection reflex

Question 7

Define: polyethia

Answer 7

presence of extra nipples

Question 8

Define: polymastia

Answer 8

extra breast tissue (can lactate and undergo malignant changes)

Question 9

Explain Secretory Differentiation (Lactogenesis I)

Answer 9

• occurs around 16th prenatal week
• main reproductive hormones required are estrogen, progesterone, placental lactogen and prolactin
• Completely dependent on hormonal changes that occur during pregnancy

Question 10

Secretory Activation (Lactogenesis II)

Answer 10

• Onset of milk secretion, up to 600ml/day
• Occurs between 30-72 hours after delivery of the placenta
• Represents the shift to autocrine (local) control
• Maintained by stimulation of the nipple and removal of milk from the breast

Question 11

List 6 risk factors for delayed onset of Lactogenesis II

Answer 11

1. Fluid volume overload in labour
2. C-section or long stage 2 labour
3. Maternal health status (diabetes, obesity, hx of breast reduction, hypoplasia, pcos, infertility, thyroid dysfunction)
4. Any maternal illness interfering with early milk removal (including Sheehans syndrome - pituitary infarct)
5. Primiparas increased risk
6. retained placental fragments

Question 12

Define Galactopoiesis or Lactogenesis III)

Answer 12

• Stage of mature milk production, later than 9-15 days after birth until beginning of involution
• Dependent on local control
• Feedback Inhibitor of Lactation (FIL) moderates milk synthesis based on fullness of the breast (More FIL present when milk accumulates in the breast)
• Prolactin receptor theory may also play a role

Question 13

Define: involution (Apoptosis of secretory cells)

Answer 13

• Occurs when the milk-producing system in the breast is no longer being used, results in cell death
• Complete involution typically takes approx 40 days after complete cessation of breastfeeding

Question 14

Explain the Milk Ejection Reflex

Answer 14

Direct stimulation of sensory neurons in the areola (by infant through suckling) initiates a neuroendocrine arc to the posterior pituitary to release oxytocin into the bloodstream

Question 15

Which hormone stimulates milk production?

Answer 15

Prolactin

Question 16

Which hormone triggers MER?

Answer 16

Oxytocin

Question 17

Which hormone is required for mammary growth and epithelial proliferation during pregnancy?

Answer 17

A form of estrogen called 17 beta-estradiol

Question 18

The elevated levels of this hormone during pregnancy prevent prolactin from influencing milk production

Answer 18

Progesterone