Mammary Glands Flashcards
6 Key Features of Mammary Gland & Development?
-Modified skin glands (sweat)
-Embryological origin
-Distinguishing characteristic of mammals
-Required to produce milk to nourish offspring
-Present in males & females (fems continue to develop at puberty & pregnancy post-natally)
-Formed by connective tissue, rudimentary duct system & secretory parenchyma
What are the age related structural & functional changes of the mammary glands?
(Slide 4 of Mammary Glands) (4 images of branching out alveoli)
1. A- Prior to puberty (rudimentary duct system= the tubules in an embryo that develop into internal reproductive organs)
2. B- After puberty (duct system = tubules/passages); oestrogen & progesterone
3. C, D- pregnancy & parturition (development & maturation alveoli): oestrogen, progesterone then prolactin
Key Difference between the mammary glands of various mammals?
Position, number of mammary glands, and internal structure of duct system draining each gland.
What is the cause of Supernumerary Teats? Where are they common, and can be done to remove them?
-Development & regression (shrinking and losing function) result in supernumerary teats
-Never develop into lactating mammary glands
-they are common in hindquarters of bovine udders
-May need surgical removal
Mammary Gland distribution in female: Dog/Canine, Cat/Feline, Horse/Equine, Pig/Porcine, Sheep/Ovine, Cow/Bovine?
Canine = 4-5 pairs, in the thoracic, abdominal, inguinal regions with multiple teat orifices (opening at the tip per gland).
Feline = 4 pairs, in thoracic, abdominal, and inguinal, with multiple teat orifices.
Equine = 1 pair, in inguinal, with two teat orifices.
Porcine = 6-7 pairs, in thoracic, abdominal, and inguinal, with two teat orifices.
Ovine = 1 pair, in inguinal, with one teat orifice per gland.
Bovine = 2 pairs, in inguinal (can extend from ulna to umbilicus), with one teat orifice per gland.
What are the 4 things that the Udder size depends on?
-Sexual maturity
-Functional status
-Individual variation
-Breed
What supports the Udder?
Suspensory apparatus.
Consists of 2 laminae which is multiple layers of connective tissue that holds the weight of the udder.
-Medial laminae (paired & elastic)
-Lateral laminae (collagenous - strong and located on the side of udder, preventing excessive movement)
What are secretory alveoli?
Multiple grape-like structures which are in the cow udder that secrete milk into ducts that transport the milk to larger ducts to be released out the teat. They are functional units of the mammary glands that produce and release milk in response to hormonal signals.
What are Myoepithelial (Basket) cells?
Structures that surround the alveoli to squeeze the content into the branching duct system for milk let down process.
6 Major Internal features of the Udder?
-All components of milk is derived from blood
-Milk is produced by secretory alveoli
-Myoepithial basket cells surround the alveoli
-Branching system ends in gland cistern
-Teat canal is the terminal area of teat which controls the milk flow
-Suckling of the newborn stimulates milk let down reflex
What are the 3 main features of Teat Closure?
-It is essential for defence against microbial influx and to stop milk releasing
-The teat sphincter contracts to form seal
-Stratified squamous epithelial cells dislodge and help ‘glue’ teat canal closed.
What is Furstenberg’s Rosette?
-Cells located at proximal end of papillary duct
-Immune function to monitor invading pathogens from environment
The name given to infection/inflammation of mammary glands?
Mastitis
Where is Milk produced and what are the components?
-In Secretory Alveoli, between blood vascular system and final product are secretory cells.
-Components: Minerals & vits.
How does the Main Blood Supply to Lactating Bovine Udder?
-Main arterial blood supply from external pudendal artery, which branches from abdominal aorta.
-Then passes through inguinal canal as blood vessel moves from being intra-abdominal to extra-abdominal.
-Then splits into cranial and caudal arteries.
The Two Venous(veins) drainage routes?
And why are they necessary?
EXTERNAL PUDENDAL VEIN:
-similar to external pudendal artery
-joins CAUDAL vena cava (goes up near spine)
SUBCUTANEOUS ABDOMINAL VEIN (Milk vein):
-only forms during FIRST pregnancy
-provides CRANIAL(under/along abdomen) drainage route
Important for: coping with volume and consistency of drainage, regardless of what animal is doing.
What does the Lymph drainage consist of?
What is its function and how does it carry it out?
Consists of blind ending capillaries in tissue.
Function: Gathers excess tissue fluid and transports back to the heart.
How: Lymph flows through superficial (close to surface of body) inguinal lymph nodes before entering body cavity via inguinal canal.
What happens when animal suffers from Mastitis?
-Mammary Lymph and inguinal, and deep inguinal nodes are enlarged.
-Palpation of lymph nodes via rectum. (can be felt on surface).
-Very painful.
What nerves supply the bovine udder?
Within udder skin: multiple innervation(process of supplying nerves) by lumbar & sacral spinal nerves.
Glandular parenchyma: innervated by genitofemoral nerve (also in milk let down reflex).
Milk Let Down Reflex process?
(Releases? Depends on? Weaning? Colostrum?)
Calf suckles/nudges udder, causing sensory input and dry skin to become erect due to the genitofemoral nerve which then sends signal to hypothalamus.
Oxytocin(hormone) is released from hypothalamus, from posterior pituitary gland into blood supply via aorta, external pudendal artery, capillary beds of udder - causing myoepithial cells to contract and squeezes alveoli into branching system and out the teat.
Milk production depends on prolactin(released by hypothalamus from anterior pituitary gland) levels & regular removal of milk. Decreases over time when calf grows.
Weaning results in regression - loss of secretory alveoli.
Colostrum - 1st milk produced after birth is important for passive immunity of neonate. (waxy and yellow in nature)
