Anatomy of the Mammary Gland

Mamma(e) (mastos, uber)

Responsible for the production of milk and colostrum (modified milk)

Represents the anatomical structure, i.e., the glandular complex that is associated with one papilla ___ (or teat of the ___)

Mammary gland

Secretory unit (not the entire anatomical structure)

Mammals

Mammary glands and the process of lactation are unique to ___.

Body, duct and sinus system, teat

Parts of the mamma

Body of mamma

Fibrous tissue and fat

Glandular epithelium (i.e., modified sweat glands)

Duct and sinus system of mamma

Overlap between body and teat of mamma

Udder

Consolidation of units of mamma

Supernumerary teats

Buds develop outside of the norm or fail to regress

Rudimentary teats

If mammary tissue fails to regress in a male, they become ___ and are found on the ventral surface (dogs and pigs) or cranial surface of the scrotum (ruminants)

Males

Mammary tissue regresses in most ___.

Species

What is the number of lactiferous units per mamma dependent on?

Lactiferous unit(s)

Glandular tissue, lactiferous duct system, lactiferous sinus(es), teat canal(s), orifice(s) in the teat

One

How many teats per mamma?

Teat canal(s)

Also referred to as papillary duct(s) or streak canal(s)

Rosette of Fürstenberg

Small folds in ruminants located between the teat canal and teat sinus

Immunological barrier against mastitis-causing pathogens

• MALT (mucosa-associated lymphatic tissue)

Mechanical seal

One

How many pairs of mammae do primates have?

Five

How many pairs of mammae do carnivores and rodents have?

Seven

How many pairs of mammae do sows have?

One

How many pairs of mammae do mares and small ruminants have?

Two

How many pairs do cattle have?

Pectoral

Position of mammae in primates

Axilla to groin

Position of mammae in carnivores, rodents, and sows

Groin

Position of mammae in mares, small ruminants, and cattle

Mammae of carnivores

Chain of mammae

• 5 pairs

  • 2 thoracic

  • 2 abdominal

  • 1 inguinal

Multiple lactiferous units per mamma

Udder of the mare

Two mammae that form an udder

Two lactiferous units per mamma

• Two teat ostia (or orifices)

Udder of small ruminants

Two mammae that form an udder

One lactiferous unit per mamma

• One teat ostium (or orifice)

Udder of the cow

Four mammae forming an udder

• Each unit is referred to as “a quarter”

• Front quarters tend to be smaller than the hind quarters

One lactiferous unit per mamma

• One teat ostium (or orifice)

Supernumerary

___ teats are common in cows.

Pointed, round, flat

The shape of the tip of the cow teat can affect milking rate and risk of mastitis.

___ : slow milking, low risk

___ : faster milking, intermediate risk

___ : fast milking, highest risk

Mastitis

One of the most economically significant diseases in dairy cattle

• Causes decreased milk production and increased costs

• Coliform bacteria are the most common cause of ___

Suspensory apparatus of the udder (uber)

Well-developed in the cow

• Dairy cow udder + milk = 70 kg or 150 lb

• Also present in the mare, doe, and ewe

Suspends the mammary gland

Paired medial and lateral ligaments

Ligaments created from the fascia of the trunk

Medial

Which is more elastic: medial or lateral ligament of mammary gland?

Middle suspensory ligament

Combined medial sheets of medial ligament

Lateral

Which is more collagenous: medial or lateral ligament of mammary gland?

Intermammary groove

Separates the left and right rows of mammary units

Axillary a., internal thoracic a., external pudendal a.

Main blood vessels that supply mammary gland in carnivores

Axillary and sternal lymph nodes, superficial inguinal lymph node

Lymph drainage of mammary gland of carnivores

Mammary gland carcinomas

Lymphatic veins communicate and can potentially have implications for metastasis of ___.

Cranial and caudal mammary a., internal pudendal a.

Blood vessels that supply mammary glands of mare and small ruminants

Superficial inguinal lymph node

Located in mare and small ruminants

External pudendal a., internal pudendal a.

Blood supply of mammary gland of cow

Superficial inguinal (or supramammary) lymph node, subiliac (prefemoral) lymph node

Lymph nodes associated with the udder

Satellite veins to the arteries of the bladder

Allows for the venous return from anywhere in the udder, even when compressed while a cow is resting

Subcutaneous abdominal (or milk) vein

Anastomosis of the cranial mammary and cranial superficial epigastric vv.

Milk well

Site where the milk vein enters the thorax