Mammary gland Flashcards
Define mammogenesis
Mammary growth at puberty or during pregnancy
Define lactogenesis
Initiation of milk secretion at parturition- colostrum production
Define galactopoeisis
Continues milk secretion during lactation
What are the benefits of lactation?
- 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
What do mammary glands originate from?
Epidermis (specialised sweat gland)
Where do the mammary ridges extend from/ to?
Axillary region to inguinal region
What gives rise to the primary mammary bud?
Mammary ridges
Discuss pre natal mammogenesis
- 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
What forms the lobules in the mammary gland?
-Groups of alveoli
What forms the lobes in the gland?
- Groups of lobes
i. e. lots of alveoli= lobule-> lots of lobules= lobe
How many canals per teat do sheep/ goats/ cows have?
1 canal per teat
How many ducts per teat do mares/ sows have?
2-3 ducts per teat
How many ducts per teat do bitches have?
3-5 ducts per teat
From what tendon does the mammary suspensory system arise?
Symphyseal tenson (lateral ligament also from external crus of inguinal ring)
Why are the udder laterally deviated in engorges/ elderly dairy cows?
-Because the elastic median ligament has been permanently overstretched
Describe the vasculature of the mammary glands
- 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.
Is there any parasympathetic innervation in the bovine mammary gland?
NO
What do the myoepithelial cells react in response to?
-The oxytocin NOT any other stimulus. i.e. they are not innervated
What mediates mammary gland growth?
Hormones
After puberty what makes the mammary ducts grow rapidly?
Presence of prolactin and growth hormone
Describe the effect of oestrogen and progesterone on mammary gland growth
- 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.
Describe mammary gland involution
- 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)
