The mammary gland (Duct and secretory system) Flashcards
Duct and secretory system
Teat :
- Streak canal
- Sphinctormuscle
- Teat cistern
Gland cistern
Duct system
Streak canal (teat canal) positron
at base of teat which milk comes from
Streak canal (teat canal) length
5 - 13 mm
Streak canal (teat canal) diameter
0.4 - 1.6 mm diameter
Streak canal lined by ……..
Cells form folds to close the canal bet. Milkings
Streak canal Produce …
Lipid like sub. Is bacteriostatic so prevent bacterial penetration and mastitis
The canal is kept closed by …
an involuntary circular sphincter muscle found in distal part of the canal
Diameter of streak canal increase by …
aging
….. canals less resistant to mastitis
Wide
Teat sphinctor muscle
At the distal part of the streak canal ( last 2 mm) Involuntary circular muscle
acts as a barrier (physical to the entry of bacteria
Teat sphinctor muscle
Tightness of sphincter muscle is …. trait depend on …
inherited
sire selection
Slow milkers has …. muscles , so …
Strong muscle so less milk and less susceptible to mastitis
Fast milkers has …. muscles , so …
Weak or patent or poor muscle easy milked and give more milk but susceptible to mastitis and leakage
Teat sphinctor muscle function
Constrict the opening (teat orifice) so keep the milk in the udder between milking
Frustenburgs Rosette …… mucosal folds
6-10
Frustenburgs Rosette Located in
internal part of streak canal , proximal part
Frustenburgs Rosette radiate in … directions
All directions to teat cistern
Frustenburgs Rosette Function
- Barrier against pathogens
- Major point for entry of leukocytes into gland
- Contain bacteriocidal protein
Teat cistern located ….
just above the streak canal
The cavity of teat
Teat cistern
Teat cistern hold …… of milk
10 - 50 ml
Into which milk drains from the gland, and from which milk is removed during the milking process
Teat cistern
Teat cistern contain in upper part …..
Accessory mammary tissue irritation overmilking of (AMT) cause infection to spread to all udder so rapid removal of teat cups
Teat cistern wall
Rich in blood vessels so when using MM the high vacuum blood congestion irritation of the lining so pulsation cycle is required
Cricoid ring
Annular folds
Bet gland and cistern
Marks the boundary bet gland and teat cistern
Gland cistern Located …
Just above the teat cistern and partially separated from it by a circular fold
A cavity act as a reservoir of milk
Gland cistern
Gland cistern hold
400 - 500 ml milk
A number of large ducts branch off from the gland cistern
Duct system
Function of duct system
- To collect the milk from the secretory tissue
- Store part of the milk between milkings
- Transport it to the gland cistern
Duct system branch and re branch into smaller and
smaller ducts and finally into the ….
Terminal ductules that drain each alveolus
Milk route
Gland cistern → 12 - 50 large collecting duct → commom duct → terminal ductule → lobule
Alveoli
Microscopic structure lined with a single layer of epithelial cells
Single layer of epiyhelial cell + blood capillary (network) + mypepithelial cell + fibroblast
Alveoli function
Take nutrients from blood to the alveolar lumen.
Functional unit of milk production
Alveoli
Drain into terminal ductules
Alveoli
Alveoli capacity
1 mm3
Lobule
10 - 250 Alveoli
Lobe
group of lobules
Milk letdown
Stimuli → Afferent sensory nerve → CNS → Oxytocin → myoepithelial cell contract → lumen of alveoli → terminal ductule → common duct → large collecting duct gland cistern → teat cistern → streak canal