mammary gland Flashcards
(19 cards)
what is mammogenesis
Mammogenesis is the formation of the glands, it is controlled by oestrogen, progesterone and permissive actions of cortisol, T3 T4, GH, IGF and insulin
what does eoestrogen and progesterone do in mammaogenesis
Oestrogen stimulates duct development, growth of adipose tissue and prolactin
Progesterone stimulate glandular tissue development (alveoli) and inhibit prolactin
what is the process of lactogenesis
Initiation of lactation, involving synthesis of milk fat and milk protein
There are two process, milk secretion and removal.
what hormones are crucial for lactogenesis
PrL secretion decreases as lactation progresses (ruminants)
PrL output from anterior pituitary controlled by 2 hypothalamic secretions
Prolactin-inhibiting hormone (PIH, or dopamine)
Prolactin-releasing hormone (PRH)
PIH is dominant most of the time
Describe the process of milk secretion
Importantly it is the synthesis of milk via intracellular transport and is discharged into the LUMEN
describe the milk removal
Importantly it is the passive removal of milk from cisterns and large ducts via reflex ejection of milk aka ‘let down’
Describe GH involved in milk production
Most likely through stimulation of IGF-I
Can ‘substitute’ for the actions of PrL in some spp.
Acts in post-absorptive state
Diverts nutrients to milk production & increasing mammary gland uptake
Exogenous administration (bST) to cows in early lactation with negative energy balance increases overall efficiency of lactation & milk production by mobilising body fat
describe the process of galactopoiesis
Maintenance of milk production through lactation by prolactin & oxytocin
FIL (feedback inhibitor of lactation) controls milk production and is present in milk
FIL acts to inhibit milk production when milk is already present in the mammary gland
FIL ––important for milking/milking frequency
desibe the main produce of mammagenosis, lactogenesis and glactopoenesis
Mammogenesis: production of the gland
Lactogenesis: Initiation of lactation, involving synthesis of milk
Galactopoiesis: Continued milk production!!!
decribe PrL actions and initiation
suckeling and visual stimuli of offspring increases oxytocin and prolactin secretion which increases lactogenesis
describe the boob anatomy
Alveoli are surronded by caliparies which produce milk.
Milk is then secreted into the lumen which is then into the ducts and further let down into the cistern.
From the cistern it is let down into the teat.
what is teh mammary gland
The gland is a Compound tubuloalveolar gland, they are enlarged modified sweat glands
what is glandular tissue
parenchymal tissue and cells
what cells contract to cause the transport of milk into the lumen from the aveloi
myoepithelial cells
describe the development stages of the mammary glands and their main growth
prepubertal - simple duct growth
postpubertal - extensive duct growth
pregnancy - alveoli growth
describe the prepubertal growth of the mammary gland
Initially isometric growth, becoming allometric closer to puberty
Initially growth independent of ovarian hormones, able to respond to ovarian hormones
Effect of E2 increases number of ductal cells & enhances proliferation of endothelial cells
GH (from pituitary) also influences growth
Increases growth of mammary parenchymal tissue
describe the postpubertal growth of the mammary gland
Increased branching of duct system
Hormone-dependent
Oestrogen
GH
Exogenous GH administration thought to increase mammary growth but not milk yield
Mammogenesis
describe the growth of the pregnancy stage of mammary growth
Growth & differentiation completed during pregnancy
Further development of ducts & alveoli
Hormones + growth factors
Growth factros involved
