12 Anatomy of the Mammary Gland Mammary gland - milk secreting structure including teats, duct system, lobes, lobules, and secretory tissueModified sweat glandExocrine glandCowLarge & in inguinal region4 teats/quarters = 4 separate glandsNo mixing of ducts across quarters
13 Anatomy of the Mammary Gland Rear quartes produce approx. 60% of the milk and the fore quarters produce the remaining 40%The size and shape of udders vary with the 1) producing ability, 2) age, and 3) genetic of the cow
14 Anatomy of the Mammary Gland CowFront & rear quarters separated by fine membraneLeft and right separated by median suspensory ligamentSupernumerary teats (some with duct and secretory system)
15 How much support is enough? High producing Holstein cowEmpty Udder = 25 kg.Milk = 30 kg= 55 kg !!!
16 Udder Support in Cow Skin Fine connective tissue below skin Connective tissue attaches front quarters to abdominal wallLateral suspensory ligaments (LSL)Median suspensory ligament (MSL)The subpelvic tendon
18 Udder Support in Cow LSL Sling around udder 2 layers Inelastic, more fibrous than MSL
19 Lateral Suspensory Ligaments Like a “hammock” around the udderFrom the pelvis to the median suspensory ligamentMostly fibrous tissueCollagenAttaches to the alveolar tissueProvides internal framework
20 Udder Support in Cow MSL Primary support Relatively elastic 2 layers Broken MSL – pendulous udder
25 Duct SystemTeat meatus, the small canal located in the end of each teat is .5 to 1 cm long and is the only sphincter in each glandSeven or eight loose folds of membrane known as furstenburg rosette are located above the teat meatusThe teat cistern, the cavity within the teat hold 30 to 90 ml of milk.
35 Nervous SystemSympathetic (efferent) (involuntary) nerves associated with arteries in the glandControl blood flow to the glandInnervation of sphincters muscles in teatsStress causes vasoconstriction decreasing milk secretion and let-downNo parasympathetic innervationNo nerves to myoepithelial cells or alveolar cells
40 Mammary Gland Development Five phases of mammary developmentPrenatal (teats & cisterns dev.)Prepubertal (limited growth)PostpubertalPregnancy (most growth)Early lactation
41 Mammary Gland Development Major development occurs at puberty and during gestationHormonesEstrogen (growth of duct system)Progesterone (development of alveolar tissue in combination with other hormones)GH (growth of duct system)Prolactin (initiation and continuity of lactation)