I.	Mammary glands are skin glands

	1.	Skin glands and their secretions

		A.	Sebaceous Glands
			a.	Associated with hair follicle
			b.	Saccular or simple alveolar structure
			c.	Lipid Secretion = Sebum
			d.	Holocrine = Whole cell degenerates
		B.	Sweat Glands
			a.	Not associated with hair follicle
			b.	Tubular or coiled structure
			c.	Salty secretion = Sweat
			d.	Exocrine = Secretion through duct	
						(No loss of cell)
		C.	Mammary Glands
			a.	Compound tubular and saccular structure
			b.	Secretion = Milk
			c.	Apocrine
				i.	Intermediate between exocrine 
					and holocrine
				ii.	Milk components secreted 
					with small amount of cellular debris

II.	External Anatomy of the Udder (emphasis on cow)

	1.	Udder
		A.	Contains one or more mammary glands
			a.	4 glands in cows (quarters)
				--completely separate ductal system
			b.	Rear quarters produce 55-60% of milk
		B.	Equivalent to Breast in Humans
	2.	Teat (papilla mammae)
		A.	Teat--Cows, Sheep, Goats, Horses
			Nipple--Pigs (also teat), Humans
		B.	Exit and delivery organ for milk
		C.	Supernumerary teats
			a.	Extra teats
			b.	50% of all female calves have them
			c.	Some connected to gland, most are not
			d.	Should be removed before one year
			e.	Sometimes seen in other mammals, 
				including humans	
	3.	Streak Canal (ductus papillaris)
		A.	Only orifice of a gland between internal 
			milk secretory system and external environment
		B.	Main barrier against infection
		C.	Kept closed by sphincter muscles
		D.	Canal patency decreases and streak canal length 
			increases with increasing lactation
	4.	Furstenburg's Rosette
		A.	Mucosal folds lining inner end of streak canal
		B.	Functions:
			a.	Prevents milk leakage when udder is full
			b.	Entry point of leukocytes into teat cistern
	5.	Teat Cistern (Sinus papillaris)
		A.	Cavity within teat
		B.	Continuous with gland cistern
		C.	Lined with longitudinal and circular folds which 
			form pockets on the inner lining of the teat.
	6.	Cricoid Rings (Annular folds)
		A.	Boundary between teat and gland cistern

III.	Udder Suspensory System (cow)

	1.	Heavy Load
		A.	High producing Holstein cow
			a.	50 lb. empty udder + 60 lbs. milk = 110 lbs.
		B.	Udder needs strong suspensory system
		C.	There are 7 tissues supporting the udder
	2.	Support (Outside-in)
		A.	Skin
			a.	Minor support
		B.	Superficial fascia or areolar subcutaneous tissue
			a.	Attaches skin to underlying tissue
			b.	Minor support
		C.	Coarse areolar or cordlike tissue
			a.	Forms loose bond between dorsal surface 
				of the front quarters and abdominal wall
			b.	Weakening causes udder to breakaway 
				from udder wall
		D.	Superficial layers of lateral suspensory ligaments
			a.	Mostly composed of fibrous tissue 
				(some elastic)
			b.	Arises from subpelvic tendon
			c.	Extend downward and forward from the 
				pubic area
			d.	Spreads out when it reaches udder continuing 
				downward over the external udder surface 
				beneath the skin attaching to the areolar 
				tissue
		E.	Deep lateral suspensory ligaments
			a.	Thicker fibrous tissues
			b.	Also arises from subpelvic tendon
			c.	Extends down and envelopes udder
			d.	Attaches to convex (bulging) lateral surface 
				of udder
			e.	Anchored by projections called lamellae
				--Pass into gland and become part 
					of internal framework of udder
		F.	Subpelvic ligament
			a.	Give rise to lateral suspensory ligaments
			b.	Attaches to pelvis at several points
		G.	Median suspensory ligament
			a.	Most important part of suspensory system
			b.	Two adjacent heavy yellow elastic sheets 
				of tissue
			c.	Arise from abdominal wall
			d.	Attach to the medial flat surface 
				of the two udder halves
			e.	Great tensile strength
			f.	Located at center of gravity

IV.	Interior Anatomy of the Udder

	1.	Make-up
		A.	Connective Tissue
			a.	Fibrous
			b.	Fatty
		B.	Secretory Tissue
			a.	Epithelium
	2.	Gland Cistern (sinus lactiferous)
		A.	Also called udder cistern
		B.	Opens directly into teat cistern
		C.	Functions for milk storage
			a.	Holds 100-400 ml
	3.	Milk Ducts & Ductules
		A.	Ducts are large, Ductules are small
		B.	Subtypes
			a.	interlobar
				i.	Primary Branching
				ii.	Between lobes
				iii.	2 layers of non-secretory cells 
					+ myoepithelial cells
			b.	intralobar
				i.	Primary Branching
				ii.	Within a lobe
				iii.	2 layers of non-secretory cells 
					+ myoepithelial cells
			c.	interlobular
				i.	Secondary Branching
				ii.	Between lobules
				iii.	1 layer of secretory cells 
					+ myoepithelial cells
			d.	intralobular
				i.	Secondary Branching
				ii.	Within lobules
				iii.	1 layer of secretory cells 
					+ myoepithelial cells
			e.	intercalary
				i.	Tertiary Branching
				ii.	From Alveolus
		C.	No uniform system of branching
	4.	Lobes and Lobules
		A.	Organization of Secretory tissues
			a.	Each gland is divided into numerous lobes
			b.	Each lobe made up of many lobules
			c.	Lobes and lobules divided 
				by C.T. encapsulations
		B.	Lobule: Contain up to 200 alveoli
	5.	Alveoli
		A.	Functional Unit 
			a.	Where milk is synthesized and released
		B.	Alveoli Cells
			a.	Secretory epithelial cells
		C.	Myoepithelial Cells
			a.	Contract in response to Oxytocin
			b.	Cause Milk letdown
		D.	Capillaries
			a.	Bring milk building blocks to Alveoli cells

V.	Vascular System

	1.	General
		A.	Vascular system bring milk precursors 
			to alveoli cells
		B.	500 to 1000 volumes of blood to make one volume 
			of milk
			a.	280 ml/sec
			b.	High producers have lower ratio 
				than low producers
			c.	Total udder blood volume is 8% of total 
				for lactating animals and 7.4% 
				for non-lactating
			d.	2-6X increase in blood flow 2-3 days 
				prepartum
	2.	Arterial System
		A.	Order of vascularization
			a.	Heart
			b.	Abdominal aorta
			c.	Internal and External iliacs
				i.	Perineal artery from internal iliac 
					supplies small portion of upper rear 
					udder
			d.	Femoral
			e.	External Pudic (or Pudendal)
				i.	Passes through inguinal canal
			f.	Mammary artery
			g.	Anterior and Posterior Mammary artery
		B.	Sigmoid flexure occurs just below inguinal canal
			a.	Allows for downward distention of udder when 
				it fills with milk
			b.	Relieves potential stress on external pudic 
				artery
		C.	No crossover of blood supply (anastomosis) between 
			udder halves
	3.	Venous System
		A.	Mammary veins leave udder antiparallel to 
			the arteries
		B.	Three veins on each side carry blood from the udder
			a.	External pudic vein
				i.	Empties into iliacs and then 
					posterior vena cava
				ii.	Also contains sigmoid flexure
			b.	Subcutaneous abdominal vein (Milk vein)
				i.	Enters body at xiphoid process 
					via milk wells
				ii.	Eventually empties into anterior 
					vena cava
			c.	Perineal vein
				i.	parallels perineal artery
				ii.	Carries <10% of blood leaving udder
		C.	Venous circle
			a.	Anastomoses between anterior and posterior 
				mammary veins
			b.	Prevents pinching off of areas of venous 
				outflow when cow is lying down
	4.	Lymphatic system
		A.	Functions
			a.	Carry extracellular fluid from udder 
				to circulatory system
				i.	Proteins aren't returned to veins 
					easily
			b.	Contain leukocytes
				i.	Especially lymphocytes 
					and macrophages
				ii.	Important in immune response
			c.	Transport of Vitamin K and Lipids
		B.	Lymph system in udder
			a.	Flows through supramammary lymph nodes
				i.	Located upper rear udder
				ii.	Usually 1 or 2 per side
			b.	Lymph vessels leave udder through 
				inguinal canal
			c.	There is extensive lymph drainage from 
				the teats
			d.	1.6 units of lymph leave udder for 
				every unit of milk produced
		C.	Edema
			a.	Excess accumulation of fluids in 
				the tissue spaces
			b.	Capillary filtration exceeds lymphatic 
				and venous drainage
			c.	Most severe in first calf heifers at calving
			d.	Severe edema can strain udder support
			e.	Exact cause unknown
				i.	Immature lymph system?
					--Slows drainage
				ii.	Increased flow of substances to udder 
					at parturition
				iii. 	Damage to capillary walls

VI.	Nervous System

	1.	Two types of nerves innervate the udder
		A.	Sensory fibers (Afferent)
			a.	Teats and skin
		B.	Sympathetic fibers (Efferent)
			a.	Arteries
			b.	No Parasympathetic innervation
	2.	Innervation of udder is sparse compared to other tissues
		A.	Four spinal nerves
			a.	First lumbar--Very fore udder
			b.	Second lumbar--Fore udder
			c.	Inguinal--Mid-udder
			d.	Perineal--Rear udder
		B.	No innervation of secretory system
			a.	Myoepithelial cells not innervated
		C.	Few nerves to interior of udder	
			
VII.	Comparative Anatomy

	1.	Generalizations and observations for eutharian animals
		A.	More specialized (evolutionarily) the gland, 
			the less the "milk" is like body fluids
			a.	More synthesis from building blocks 
				from blood, rather than components of blood 
				itself.
		B.	Males have rudimentary ducts and teats
			Exceptions:
			a.	Male rats don't have teats
			b.	Stallions have no mammary structures at all
		C.	Generally milk is only used by young
		D.	Cows and goats can produce more than needed by young
			a.	Cow can produce 10-20X their weight in milk 
				in one year
		E.	Location of mammary glands
			a.	Anterior (Thoracic or Pectoral)
				i.	Primates, elephants, seacows, bats
			b.	Abdominal
				i.	Litter bearers
				ii.	Either side of midline from one end 
					to the other
			c.	Posterior (Inguinal)
				i.	Ungulates, whales

	2.	Cattle
		A.	4 mammary glands (quarters)
			a.	Inguinal
		B.	4 teats (one per gland)
		C.	1 streak canal per teat
	3.	Sheep & Goats
		A.	2 mammary glands
			a.	Inguinal
		B.	2 teats
		C.	1 streak canal per teat
		D.	Vascular & Nervous System similar to Cattle
	4.	Horses
		A.	4 mammary glands
			a.	Inguinal
		B.	2 teats
			a.	Flat and broad with blunted tips
			a.	Not spherical shaped like cows, sheep, 
				and goats
		C.	2 streak canals per teat
		D.	Vascular & Nervous System similar to Cattle
	5.	Pigs
		A.	4-9 pairs of mammary "glands"
			a.	Abdominal (Pectoral to inguinal)
			b.	Anterior glands produce more milk	
		B.	8-18 nipples
			a.	Supernumaries occur
			b.	Inverted teats an inherited condition
				i.	Nipples fail to project from 
					the surface of the gland
		C.	2 streak canals per nipple 
			a.	Drain sectors (simple glands)
				i.	Similar to a lobe in other species
			b.	Small teat cisterns
				i.	Dilation of streak canal = ampulla
		D.	2 sectors per gland
			a.	2 duct systems per gland
		E.	Blood supply
			a.	External thoracic (anterior mammary)
				i.	Supply anterior glands
			b.	External Pudendal (posterior mammary)
				i.	Divide into abdominal and inguinal
			c.	Anastomose with each other
		F.	Lymphatics
			a.	Supramammary lymph node
				i.	Inguinal
			b.	Mediastinal cranial lymph node
				i.	Diaphragm area
			c.	Ventral superficial lymph node
				i.	Cranio-dorsal to shoulder blades
	6.	Humans
		A.	2 mammary "glands"
			a.	Pectoral
			b.	Breasts
		B.	1 nipple per breast
			a.	Surround by pigmented area called areola
			b.	Rough, bumpy due to modified sebaceous glands 
				and sweat glands
				i.	Montgomery's follicles
		C.	10-20 streak canals per nipple
			a.	Also called lactiferous ducts
		D.	10-20 sectors (simple glands or lobes) per breast
			a.	Ampulla takes place of teat and gland cistern
		E.	Suspensory System
			a.	Suspensory ligaments of Cooper
				i.	Run from skin to deep fascia 
					between sectors (lobes)
			b.	Breast contain large amounts 
				of adipose tissue
				i.	Especially when non-lactating
		F.	Blood Supply
			a.	External thoracic arteries and veins
		G.	Nervous system
			a.	Fourth intercostal nerve 
				i.	Sensory to nipple
				ii.	Very sensitive, causes nipple 
					to become erect
			b.	Sympathetic to arterials
		H.	Lymphatics
			a.	Numerous nodes
				i.	Palpation is indicator 
					of breast health
			b.	Breast, under arm, and in neck