Please enable JavaScript.
Coggle requires JavaScript to display documents.
The Mammary gland (Lactation cycle (stops at 305 days of lactation…
The Mammary gland
Lactation cycle
increase for the first 3-4 weeks then slowly decline
stops at 305 days of lactation
to prepare for next lactation
involution
requires at least a month
can be induced by estrogen & progesterone administration
enhanced by GH
acts on postabsroptive nutrients
results in mobilization of body fats used in milk formation
increased by photoperiod exposure
Anatomical aspects
parenchyma (milk-secreting cells)
develops through proliferation of epithelium
arise from primary mammary cord
form alveoli
release fat into milk
involves constriction of plasma membrane around fat droplet
most important energy source in milk
begins at puberty
remains relatively undeveloped until pregnant
accumulated milk stored in alveoli
cistern in cow and doe
able to synthesize & store larger amounts of milk
develops as paired structure
position varies in different species
closely apposed to each other (udder) in domestic animal
suspensory system is developed
avoid mammary gland system break down from the weight of milk
Colostrum
milk formed before parturition
lactogenesis occurs without milk removal
important to ingest
passive immunity
immunoglobulins
can be absorbed through gut in the first 24-36 hours
rich in vitamin A, caseins & albumins
low lactose
Lactogenesis
prolactin
release together with manipulation of teat
inhibited by dopamine
stimulated by vasoactive intestinal peptide
short-lived surge occurs immediately after onset of milk removal
other major hormone: growth hormone
promote additional milk production
milk proteins & lactose are synthesized in ER (Golgi vesicles)
release through exocytosis
lactose is the main carbohydrate
main proteins are caseins
can be removed as a curd
through curding / coagulation
albumins & globulins remain as whey
maintained by
milk removal
from mammary gland
myoepithelial cells surround alveoli & duct
responsive to oxytocin
cause contraction
milk letdown
Diseases
directly
neoplasia
dog is most susceptible
exposure of mammae to estrogen & progesterone
mammary tumor
mastitis
cause by injury to teat canal
repeated stretching
effect formation of CT within the udder
limits area into which ducts & alveoli can proliferate
reducing milk-producing potential
indirectly
transfer of RBC agglutinating antibodies to fetus through milk
common in horse
hemolytic crisis between 24-48 hours after delivery
die unless given therapy
hypocalcemia
increase movement of calcium into blood
lose ability to maintain normal muscle activity
Control of mammogenesis
initial development is under control of embryonic mesenchyme
first nursing
good carbohydrate store in animals having 1-2 offspring
can stand a longer interval to first suckling