Mammary

Question 1

What are the 4 stages of mammary gland development

Answer 1

1. Before birth
2. From birth to pregnancy
3. During pregnancy
4. During lactation

Question 2

What occurs during stage 1 of mammary gland development

Answer 2

1. Mammary buds invaginate into the mesodermal fat pad to produce teats
2. Primary sprouts form the gland and teat sinuses
3. Secondary sprouts arise from the primary sprouts to produce lactiferous ducts

Question 3

When does mammary growth begin to get influenced by hormones?

Answer 3

During stage 2

Question 4

What hormones affect mammary gland growth, what do they do, and how are they released

Answer 4

E2: stimulates duct lengthening and branching
P4: stimulates duct development and enlargement
They are released in a cyclical manner

Question 5

Describe the growth of mammary glands during each hormonal phase

Answer 5

Estrogenic phase: allometric (faster than the rest of the body)
Progesterone phase: isometric (same rate as the rest of the body)

Question 6

What occurs during stage 3?

Answer 6

Fatty pad is replaced with ducts, alveoli, and blood vessels

Question 7

What causes the flow of milk from the alveoli?

Answer 7

Contraction of Myoepithelial cells on the outer surface of the alveoli

Question 8

How are alveoli arranged?

Answer 8

Into lobules separated by interlobular connective tissue

Question 9

Describe the path of milk in the Mammary gland

Answer 9

1. alveolar lumen
2. intrAlobular ducts
3. Small intErlobular ducts
4. Increasingly larger ducts
5. Lactiferous ducts
6. Lactiferous sinus

Question 10

What are the functions of the teat

Answer 10

1. Provide prehensile structure for the offspring to suckle
2. Restrict leakage from the gland between nursing (fatty plug)
3. Provide sensory input for the milk-ejection reflex when offspring suckles

Question 11

What are the laminae that suspend the udder?

Answer 11

Lateral suspensory laminae: dense CT, arises from the external inguinal ring and simphyseal tendon
Medial suspensory laminae: elastic CT, arises from the tunica flava and the simphyseal tendon

Question 12

What arteries supply the mammary gland?

Answer 12

Cranial mammary arteries: from the external pudendal artery branch of the external iliac artery
Caudal mammary arteries: ventral perineal artery branch of internal iliac artery

Question 13

What veins drain the mammary glands

Answer 13

External and internal pudendal veins

Question 14

What nerves innervate the mammary gland

Answer 14

Lumbar: skin sensation and deeper parts of the teat wall (genitofemoral nerve)
Sacral: supplies skin of hind quarters