Mammary gland

Question 1

Define mammogenesis

Answer 1

Mammary growth at puberty or during pregnancy

Question 2

Define lactogenesis

Answer 2

Initiation of milk secretion at parturition- colostrum production

Question 3

Define galactopoeisis

Answer 3

Continues milk secretion during lactation

Question 4

What are the benefits of lactation?

Answer 4

• Provides social development and bonding
• Means neonates aren’t dependant on another food source
• Natural form of contraception
• Offspring can continue development outside of uterus

Question 5

What do mammary glands originate from?

Answer 5

Epidermis (specialised sweat gland)

Question 6

Where do the mammary ridges extend from/ to?

Answer 6

Axillary region to inguinal region

Question 7

What gives rise to the primary mammary bud?

Answer 7

Mammary ridges

Question 8

Discuss pre natal mammogenesis

Answer 8

• Mammary ridges= thickened epithelium. The mammary ridges give rise to primary mammary bud
• Primary mammary bud pushes down into dermis
• Becomes secondary mammary bud and starts to branch out
• Canalisation occurs to form lactiferous ducts

Question 9

What forms the lobules in the mammary gland?

Answer 9

-Groups of alveoli

Question 10

What forms the lobes in the gland?

Answer 10

• Groups of lobes

i. e. lots of alveoli= lobule-> lots of lobules= lobe

Question 11

How many canals per teat do sheep/ goats/ cows have?

Answer 11

1 canal per teat

Question 12

How many ducts per teat do mares/ sows have?

Answer 12

2-3 ducts per teat

Question 13

How many ducts per teat do bitches have?

Answer 13

3-5 ducts per teat

Question 14

From what tendon does the mammary suspensory system arise?

Answer 14

Symphyseal tenson (lateral ligament also from external crus of inguinal ring)

Question 15

Why are the udder laterally deviated in engorges/ elderly dairy cows?

Answer 15

-Because the elastic median ligament has been permanently overstretched

Question 16

Describe the vasculature of the mammary glands

Answer 16

• Thoracic glands= mammary arteries are branches of thoracic and pectoral arteries
• Abdominal glands= branches of the cranial/ caudal superficial epigastric artery
• Inguinal glands= mammary arteries are branches of the external pudendal arteries.

Question 17

Is there any parasympathetic innervation in the bovine mammary gland?

Answer 17

NO

Question 18

What do the myoepithelial cells react in response to?

Answer 18

-The oxytocin NOT any other stimulus. i.e. they are not innervated

Question 19

What mediates mammary gland growth?

Answer 19

Hormones

Question 20

After puberty what makes the mammary ducts grow rapidly?

Answer 20

Presence of prolactin and growth hormone

Question 21

Describe the effect of oestrogen and progesterone on mammary gland growth

Answer 21

• Allometric growth occurs
• During oestrus/ menstrual cycles the ducts begin to branch under effect of E2. BUT number of alveoli increases under influence of P4.

Question 22

Describe mammary gland involution

Answer 22

• As need for milk decreases more is left inside the gland–> pressure increases and causes pressure atrophy resulting in cells becoming less functional)
• Cells become atrophic and die (apoptosis)