VMED 5127 Dr. Al Mammary Glands
Terms in this set (27)
- The most common inflammation of the mammary gland in large animals
- Has significant economical cost to the dairy industry
What are the 2 secretion modes of the mammary glands? And what to they each secrete?
1. Apocrine - secretes lipids by budding, some loss of cytoplasm
2. Merocrine- secretes proteins and carbs via exocytosis, no loss of cytoplasm
What 6 things does milk contain?
4. Immunoglobulins (mostly IgA)*
- Thin, yellow milky fluid secreted a few days before or after parturition.
- 75% of passive immunity is transferred this way (via gamma globulins)
- It also acts as a laxative and stimulates the expulsion of the meconium.
- Important in pig, ox, small ruminants and mares because the placentas in these animals don't allow in utero transfer of immunoglobulin to the fetus.
Placentas in humans and carnivores ----- transfer of immune substance during the ------
during the last weeks of pregnancy
What 3 stimuli stimulate milk production?
3. Handling newborn
Anticipation of nursing stimulates a surge in the release of these 2 hormones.
2. Oxytocin (from the hypothalamus)
- Stored in the Herring Bodies of the Pars Nervosa.
- Initiates the milk ejection reflex by inducing contractions of Myoepithelial Cells around the Mammary Alveoli (secretory units).
- Ducts contract and force milk to be expelled into the Excretory Duct System.
What is meconium?
- A dark green material in the intestine of a Full Term Fetus.
- its a mixture of intestinal gland secretions and some amniotic fluid.
- It is the first intestinal content to be expelled by the newborn.
Lobule in a mammary gland
Group of alveoli
Lobules in the mammary gland are separated by ---
Interlobular connective tissue septa
Alveolar epithelium varies from ---- to ---- based on -----
- Varies from columnar to low cuboidal
- Based on the alveolar secretory activity
Are all the lobules in the mammary gland at the same secretory phase?
Are the alveolar constituents of a lobule in a mammary gland at the same secretory phase?
All secretory units in a mammary gland (alveoli) are surrounded by these 2 things.
1. Extensive vascular plexus
2. Lymph capillaries
Alveoli become distended with ----, and no further secretion happens until the alveoli are emptied.
- In several days, unremoved milk causes some epithelial degeneration (milk gets absorbed)
Apocrine method of secretion
- Lipid droplets move toward the apical portion of the epithelial lining and protrude into the alveolar lumen.
- These lipid droplets are released with varying amounts of cytoplasm and enclosed by a plasmalemma.
Merocrine method of secretion
- Vesicles filled with protein micelles and carbs in the alveolar epithelial lining move toward the epithelial cell surface.
- Their contents are released via exocytosis
Path milk travels from the mammary glands (starting at the interlobular ducts) to the baby's mouth.
Large Lactiferous ducts
Teat base (Gland sinus)
Teat External Orifice
Does just one or do several lactiferous duct(s) empty into the teat base/gland sinus?
What type o epithelium is within the interlobular ducts?
What type of epithelium lines the interlobular ducts?
Proximally: Simple cuboidal
Distally: Stratified cuboidal
Epithelium of the teat sinus?
Epithelium of the teat canal?
- Lamina propria has smooth muscle bundles which form a sphincter to hold milk until it is forced out by milking or sucking
Look at different pictures of teats on the powerpoint
Pig and Mare: 2 teat sinuses, 1 nipple
Carnivore: 5 teat sinuses, 1 nipple
Cow: 2 teat sinuses, 2 nipples
Small Ruminants: 1 teat sinus, 1 nipple
What is an annular fold?
Mucosal fold that separates between lactiferous gland sinus and lactiferous teat sinus
Unlactating (inactive) Mammary Gland
- Composed of mainly isolated tubules, few small alveoli, abundant septal CT and fat cells.
- Alveoli are lined by low cuboidal epithelium.
- Surrounded by 4-6 distinct myoepithelial cells.
- Casin bodies (corpora amylase) are in the mammary tissue
- Less parenchyma and more stroma
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