Mammary gland and lactogenesis Flashcards
Define mammogenesis?
— Mammary growth at puberty or during pregnancy.
Define lactogenesis?
— Initiation of milk secretion at parturition — production of colostrum.
Define galactopoiesis?
— Continued milk secretion during lactation.
Where do mammary glands originate from?
. Mammary glands are glands that originate from the
epidermis.
. They arise along two lateral lines on the ventral
surface of the developing fetus.
. These lines are called mammary ridges.
. Mammary ridges extend from the axillary region
to the inguinal region.
. Number and position of glands depend on the
species.
What is the anatomy of the mammary gland?
Glandular tissue with secretory epithelial cells and excretory ducts.
Excretory ducts empty into the gland cistern.
Epithelial cells surround a spherical lumen: alveolus (also called alveolar cells).
Myoepithelial cells surround each alveolus and the ducts.
Contraction of rnyoepithelial cells propels the milk out of the alveoli
Groups of aveoli form lobules
Groups of lobules form the the lobes
Which animals have two canals per teat?
Camel.
Which animals have 1 canal/cistern per teat?
Cow, ewe and goat.
Which animals have 2-3 ducts per teat?
Mare and sow.
Which animals have 5-6 ducts per teat?
Bitch and queen.
Which animals have 8-10 ducts per teat?
Primates and elephants.
How are monotremes (platypus) different with regards to milk secretion?
— Mammary tissue is essentially a band of sweat
glands.
— No teats — the milk runs out along the hair
shafts.
How is the udder suspended in ruminants?
The ruminant mammary gland (udder) is
supported by a strong suspensory ligament,
divided into two parts:
1. Medial suspensory ligament arising from
the symphyseal tendon (attaches the prepubic
tendon to the pubic symphysis). Mainly connective tissue.
2. Lateral suspensory ligaments running from
the symphseal tendon and the external crus
of the inguinal ring, assisted by the medial
femoral fascia, and then runs ventrally over the
lateral aspect of the udder. Inelastic connective
tissue.
Thoracic glands are supplied by what vasculature?
mammary arteries are branches of thoracic and pectoral aa.
Abdominal glands are supplied by what vasculature?
Branches of the cranial and caudal superficial epigastric aa.
Inguinal glands are supplied by
Mammary aa. which are branches of the external pudendal a.
Why is lymphatic drainage important to consider when removing a mammary tumour?
Lymphatic drainage of dogs, it drains either caudally or cranially respective to area but the middle glands go each way and we don’t know which way it is this
very important when removing mammary tumours as need to consider the lymph drainage.
What is venous and lymphatic drainage of the bovine mammary gland?
Venous drainage is via:
— The external pudendal veins into the ext. iliacs then caudal vena cava.
— The superficial epigastric veins (aka milk veins) then to the internal thoracic vein, then the cranial vena cava.
— The perineal veins into the internal pudendal vein
then the caudal vena cava.
Lymphatic drainage arises in lobules, not in alveoli. It leaves gland via mammary lymph nodes (upper rear of udder in cattle).
What is the innervation of the bovine mammary gland?
No parasympathetic innervation.
Four spinal nerves supply them 1st and 2nd lumbar, inguinal and perineal.
What is isometric growth and allometric growth?
Isometric growth means that all the body parts grow at approximately the same rate and the adult proportions are not significantly different from those of the
juvenile.
Allometric growth. the increase in size of different organs or parts of an organism at various rates.
How does mammary gland involution occur?
As the need for milk as sole nutrient begins to
decrease pressure builds up in the gland.
Cells become less functional (pressure atrophy).
Cells become atrophic and die by apoptosis.
Immune cells (lymphocytes and macrophages)
invade the tissue (they participate in the production
of IgG for the next lactation).
Cells will remain non functional until next
pregnancy.
What does colostrum contain?
Contains more proteins, fat, minerals and vitamins
than regular milk. However lactose concentration is
lower.
•Proteins: transfer of IgG, IgM, IgA from blood to
milk.
•Supplies the newborn with immunoprotection.
— Very important in equidae and bovidae.
— In primates and partially in dogs & cats this is also
provided by blood exchange through the placenta.
Milk has the same osmolarity as what?
Blood
Milk’s pH is?
6.6-6.9
What synthesises the majority of milk components and why?
Epithelial cells synthesise the majority of milk components due to high number of mitochrondria.
Mitochondria: synthesis of fatty acids and non
essential amino acids.
RER: synthesis of secretory proteins (Golgi).
SER: synthesis of phospholipids and triglycerides.
