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37 Cards in this Set
- Front
- Back
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What are mammary glands? |
Modified sweat glands whose secretion nourishes the young |
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What is the gland shape of the mammary glands? |
Compound tubuloalveolar, grouped into lobules |
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How do the mammary glands develop? |
As epithelial buds that grow into the underlying mesenchyme from linear ectodermal thickenings (mammary ridges) |
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What is the extent of the mammary ridges in different species? |
Carnivores/Pigs: extend from axilla to the groin
Elephants: limited extent, restricted to axilla
Humans: limited extent, thorax
Ruminants/Horses: limited extent, groin |
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What are supernumerary teats? |
More buds appear than survive in the adult, most extra buds regress but some persist = supernumerary teats |
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Why are supernumerary teats usually removed? |
They may interfere with milking and are unsightly |
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What path does milk take through the udder? |
The glandular tissue is arraged in lobules of about 200 alveoli
Milke drains to an intralobular duct that joins thers to form a larger interlobular duct
Interlobular ducts lead into lactigerous ducts that convey the milk to the lactiferous sinus (a large cavity) |
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Why are lactiferous ducts especially different from most ducts? |
They have alternating narrow and dilated portions
- contraction of the muscular wall of the narrow portions holds the milk in the expansions before it is "let down" when the calf suckles or she is milked |
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Where is the papillary duct found? |
At the tip of the teat where the orifice is surrounded by a smooth muscle sphincter |
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Why do some males have rudimentary teats? |
Mammary buds also form in male embryos and persist to give rise to the rudimentary teats found on the ventral surface of the trunk (carnivores and pig) or on the cranial surface of the scrotum (ruminants)
*Occasionally show up in horses beside the prepuce, but regress completely in rats |
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How many pairs of mammary glands do dogs have and where are they located? |
5 pairs, spread along the ventral aspect of the trunk |
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What are the positions of the 5 pairs of mammary glands in the dog? |
2 Thoracic pairs (most cranial) 2 Abdominal pairs 1 Inguinal pair (most caudal) |
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How many openins are at the tip of each teat in a dog? |
10-12 openings |
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How any pairs of mamary glands does the cat have? |
4 pairs |
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How many openings are at the tip of a cat's teat? |
4 to 8 openings |
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Where does blood going to the mammary gland come from in the dog/cat? |
Cranial mammary glands: - Lateral thoracic comes from the axillary - Cranial superficial epigastric and intercostal arteries also help, come from the internal thoracic
Caudal mammary glands: - Caudal superficial epigastric artery comes from the external pudendal - Branches of cranial abdominal and deep circumflex iliac arteries
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Where does lymph from the mammary glands go? |
From cranial 3 (2 in cats) glands, goes to axillary, accessory aillary and sternal nodes
From 2 caudal sets goes to superficial inguinal (mammary) node - located dorsal to the caudal border of the inguinal mammary gland (or in the cat, also to the caudal epigastric nodes along the course of the caudal epigastric vessels)
3rd pair in the dog drains toward axillary lymph node but may also drain caudally |
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How is lymphatic drainage from mammary glands different between the dog and cat? |
Lymph vessels do not cross midline or penetrate the thoracic wall in cats |
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How many openings are on each teat in the horse? |
Two or three - each leads to small lactiferous sinus associated individual set of lactiferous ducts |
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What are the ligaments of the horse's udder? |
Medial elastic and lateral fibrous ligaments that encapsulate the udder
The medial ligaments are the plane between the apposed surfaces of the udder halves |
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What is the blood supply to the udder in the horse? |
External pudendal artery
External pudendal vein drains it, but doesnot follow the usual course through the inguinal canal
*Same in cow: subcutaneous venous connection with superficial vein of the thoracic wall develops during first pregnancy = alternate route of drainiage |
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What is the lymph drainage in the horse udder? |
To the mammary (superficial inguinal nodes) |
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What gives cutaneous innervation to the udder in the horse? |
Pudendal nerve - nerves of the flank and descending mammary branches
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Which spinal nerves supply the udder of the horse? |
L2-4 and S2-4
Substance of the gland is supplied by the genitofemoral nerve (L3-4) |
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How many mammary glands does the cow have? |
4 |
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What is the groove that divides the cow's udder in half? |
The median groove |
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What is the medial lamina of the cow? |
Medial lamina is part of the fascia that suspeds the cow's udder
Arises from the tunica flava and a small part from the symphysial tendon
Made of elastic tissue |
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What is the lateral lamina of the cow? |
The more lateral ligament that helps suspend the cow's udder
Arises from external crus ofthe inguinal ring and (behind this) from the medial femoral fascia
composed of dense connective tissue |
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What is the path of milk through the cow's udder? |
Branching duct system separated from its neighbours by connective tissue
the alveolar secretory units lead to small exretory ducts
These combine with others until there are about a dozen wide lactiferous ducts
These then converge on a large sinus situated in the lower part of the quarter and extend into the teat |
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What are milk knots? |
The lactiferous ducts of the cow have alternating wider and narrower sections
More superficial dilations may be palpable when distended with milk and are then known as "milk knots" |
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What is the vasculature of the cow's udder? |
Main supply from external pudendal artery - it passes through the inguinal canal along with a satellite vein, lymphatics and nerves - when it reaches the base of the udder it divides into a cranial and caudal branch, embedded in the gland substance
The caudal mammary branch anastamoses with a division of the ventral perineal artery - restricts its distribution to mammary lymph nodes and a limited portion of the hindquarter |
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What is the venous drainage of the cow's udder? |
Venous ring above the udder formed by paired veins connected across the midline by transverse vessels
Effected by: - the external pudendal veins, which pass through the inguinal canals - the subcutaneous abdominal ("Milk") veins which run under the skin and disappear into "milk wells" in the body to wall to discharge into the internal thoracic veins - internal thoracic then drains into the cranial vena cava |
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How is the papillary duct different in sheep compared to cows and goats? |
In sheep there is no sphincter muscle to help close the papillary duct |
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How many pairs of teats do pigs have? |
7 pairs arranged in a double row extending from thorax to groin |
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How many openings does each teat have in a pig? |
2 openings leading to independent gland units |
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What is the blood supply to the pig's mammary glands? |
Internal thoracic and cranial and caudal superficial epigastric arteries
Venous drainage is satellite |
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What is the lymph drainage of the pig's mammary glands? |
Lymph from first two or three pairs leads to ventral superficial cervical nodes
The rest drain into the superficial inguinal |
