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Milk's 4 main abilities or attributes
- 1. Antimicrobial
- 2. hydration
- 3. thermoregulation
- 4. source of Calcium via caseins
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Mammary glands are most closely related to what type of gland?
Apocrine gland or scent gland
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How many mammary glands and openings per teat do kangaroos have?
4 abdominal with 15 openings per teat
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How many mammary glands and openings per teat does a cat have?
- 2 Thoracic+ 6 Abdominal=8
- with 3-7 openings/teat
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How many mammary glands and openings per teat does a dog have?
- 2 Thoracic + 6 abd + 2 inguinal=10
- 8-14 openings/teat
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How many mammary glands and openings per teat does a mouse have?
- 4 thoracic + 2 abd + 4 inguinal=10 with
- 1 opening/teat
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How many mammary glands and openings per teat does a rats have?
- 4 thoracic + 4 abd + 4 inguinal=12 with
- 1 opening per teat
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How many mammary glands and openings per teat does a pig have?
4 thoracic + 6 abd + 2 inguinal= 12 with 2 openings per teat
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Polythelia
An extra nipple only
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Polymastia
An extra, full mammary gland with lactation
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Ducts and all the structures we are growing are made of what type of cells?
Epithelial cells
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What is responsible for the opening or lumen of the end duct?
apoptosis
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How is it that ducts don't ever grow more than 0.25mm to each other?
Local growth inhibiting factors are secreted
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What signals the ducts not to grow any further?
The outer edge of the fat pad
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Parenchyma is a way of referring to what?
to all the active secretory tissue of an organ.
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2 ways breasts can grow by are:
- Fat deposition
- Epithilelial cells growing & multiplying
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What signals the ducts not to grow any further?
The outer edge of the mammary fat pad or local growth inhibiting factors
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What are the 2 phases of allometeric growth prior to pregnancy?
Puberty and conception
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Each alveolus
measures?
contains how many cells?
holds how much milk?
- each is ~100 microns across
- contains 100 epithelial cells
- holds ~ 1/5 drop if milk
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150-220 alveoli are arranged into a ?
lobule
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multiple lobules are arranged into?
lobes
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This hormone is the driving force in MG development
Estrogen
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Most common examples of Selective Estrogen Receptor Modulators (SERMs) are?
tamoxifen and raloxifene, they function to block estrogen from binding the estrogen receptor & activating target genes.
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Steroid hormones (estrogen, progesterone, androgens, glucocorticoids) signal via what type of receptor?
nuclear hormone receptors that act as transcription factors after binding hormone.
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Estrogen stimulates the ducts to grow via formation of ?
end buds
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Estrogen primes the epithelial cells to make?
- progesterone receptors at the level of gene transcription
- -cells are able to repond to P due to increased levels of the PR
- -E +P leads to increased branching of the ductal structures
- -P alone doesn't do much, req.s E
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About how many epithelial cells make up an alveolus?
~100
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From what type of gland did the mammary gland most likely evolve?
Apocrine
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Allometric growth occurs during which 2 stages of mammary gland growth/function?
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What does hematoxylin stain?
all cell nuclei
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What hormones are required for FULL lobulo-alveolar development?
estrogen+progesterone+prolactin+growth hormone
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What is the abundant, antibacterial, structural protein found inside the bovine teat?
keratin
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What are the primary structures that "direct" or "facilitate" ductal elongation into the mammary fat pad during growth?
end buds
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During what periods of development do end buds appear?
onset or just before puberty and proestrus/estrus of each cycle
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Describe the process of mammary gland development in the embryo
- 1.ectodermal thickening due to cell migration
- 2. mesoderm surrounds ectodermal thickening to become future stroma
- 3. formation of mammary band/streak/line/milk ridge
- 4. segregation into discrete hillocks (future site of MG)
- 5. mesenchyme pushes up future nipple region
- 6. epidermal sprout encroaches into underlying mesenchyme
- 7. mesenchyme induces epithelial sprout to grow inward due to growth factors
- 8. formation of bld vessels around epithelial sprout
- 9. simply branched structure present at edge of fat pad by birth.
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How does the process of MG development in the embryo differ in males and females?
Mesenchyme responds to testosterone from male to pinch off epithelial connection in certain species.
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What are the parts of a cow's teat?
- teat cistern
- streak canal
- sphincter
- furst rosette
- keratin plug
- cricoid rings
- keratinized lining
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What are the5 methods you can use to measure the growth of the MG?
- 1. DNA/RNA content-reqs equip & kill animal
- 2. count # of cells- very difficult & kill animal
- 3. MG weight- kill animal
- 4. Label dividing cells- cell proliferation
- 5. MG volume- not accurate, doesn't acct for parenchyma, milk volume alters
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Estrogen's role in MG development/growth
- 1. Stimulates ductal growth
- 2. stimulates terminal end buds
- 3. cooperates w GH/IGF-1 during puberty
- 4. helps induce IGF-1
- 5. induces progesterone receptors/ expression
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What is Progesterone's role in MG growth and development?
- 1. Stimulates ductal branching
- 2. Stimulates alveolar development
- 3. Cooperates w prolactin during pregnancy
- 4. Induces HGF/works via HGF
- 5. Acts on progesterone receptors
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Carnoy's fixative is used to stain what?
the nuclei of epithelial cells, will turn them purple when making whole mounts.
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