Mammary gland development Flashcards
Define Mammogenesis
Mammogenesis: Mammary growth at puberty or during pregnancy.
Define Lactogenesis
Lactogenesis: Initiation of milk secretion at parturition – production of colostrum.
Define Galactopoiesis
Galactopoiesis: Continued milk secretion during lactation.
Where do mammary glands develop?
They arise along two lateral lines on the ventral surface of the developing fetus called mammary ridges. The mammary ridges extend from the axillary region to the inguinal region.
How do mammary glands develop?
Mammary glands are glands that originate from the epidermis, they are thickened epidermal tissue that develops into a primary mammary bud. This bud then branches and grows deeper into the dermis and becomes a secondary mammary bud.
These then canalise and become lactiferous ducts
Each alveolus is surrounded by ……………
Myoepithelial cells surround each alveolus and the ducts.
Contraction of myoepithelial cells propels the milk out of the alveoli into the ducts
What are the lobules?
Groups of alveoli form the lobules (~200 alveoli surrounded by connective tissue) and groups of lobules form lobes
Dog teats:
How many?
How many canals per teat?
Position?
Approx 10
8-22
Abdominal
Cat teats:
How many?
How many canals per teat?
Position?
8 teats
4-8 canals
Abdominal
Sow teats:
How many?
How many canals per teat?
Position?
8-18 teats
2 canals
Abdominal
Cow teats:
How many?
How many canals per teat?
Position?
4 teats
1 canal
Inguinal
Mare teats:
How many?
How many canals per teat?
Position?
2 teats
1 canal
Inguinal
How are marsupial mammary gland different?
Mammary glands within the pouch.
Young form a direct seal around the teat.
How are monotremes mammary gland different?
Mammary tissue is essentially a band of sweat glands.
No teats – the milk runs out along the hair shafts.
Describe the suspensory ligaments of the mammary glands
- Medial suspensory ligament arising from the symphyseal tendon (attaches the prepubic tendon to the pubic symphysis). Mainly yellow elastic connective tissue.
- Lateral suspensory ligaments running from the symphyseal tendon and the external crus of the inguinal ring, assisted by the medial femoral fascia, and then runs ventrally over the lateral aspect of the udder. Inelastic connective tissue.