evolution of the mammary gland and secretions
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EVOLUTION OF THE MAMMARY GLAND AND SECRETIONS. Why is the mammary gland really a gland of reproduction?. MAMMARY GLAND. Gland of Reproduction Development is tied to hormones and physiology of reproduction. Purpose is to nuture young!!

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evolution of the mammary gland and secretions

EVOLUTION OF THE MAMMARY GLAND AND SECRETIONS

Why is the mammary gland really a gland of reproduction?

mammary gland
MAMMARY GLAND
  • Gland of Reproduction
  • Development is tied to hormones and physiology of reproduction.
  • Purpose is to nuture young!!
  • Huge female expenditure for something outside their own body!
  • Develop offspring/ species survival!
mammals
MAMMALS
  • mamma: latin word - breast / milk gland
  • Kingdom: Animals
  • Phylum: chordata
  • Sub phylum: vertebrae
  • Class: mammalia
  • > 4400 species ( good info on ~150)
  • Evolved 250 million years ago (dinosaurs- 65)!
mammals1
MAMMALS
  • WHAT ARE 2 DISTINCT FEATURES OF MAMMALS?
  • HAIR?
  • MAMMARY GLANDS!
subclass prototheria
SUBCLASS: PROTOTHERIA
  • NO PLACENTA
  • Egg laying mammals
  • Lactation preceded placentation!
  • One order: Monotremata
  • 3 species?
  • Mammary glands: no teats!
  • Tubules with myoepithelial tissue
  • Young have strong forepaws/ poorly developed hindlimbs
slide10

Mammary gland:

  • no teats
  • tubules
  • myoepitelial cells
  • milk forced onto hair
slide11

Female lays eggs 2 weeks post mating

  • 10 - 14 day incubation period
  • 1-2 eggs
  • Young: 350 mg at birth; 3-4 mo.- 1/2 adult wt.
slide12

WHY MAMMALS?

Less young but better survival!

  • Protect egg!

Nourish young!

WHY MAMMARY GLANDS?

echidna
ECHIDNA
  • Lay eggs but transfer to temp. brood pouch
  • 10 day incubation
  • 3-4 month lactation
  • special areas called areola in pouch: tubules
subclass theria
SUBCLASS: THERIA

HAVE PLACENTA!

metatheria
METATHERIA
  • Give birth to live young but not a true placenta: chorio-vitelline
  • One order: Marsupials
  • Pouched animals
  • 3-4 week gestation
  • Embryo born w/ highly dev. forepaws
  • Adaptation: animals move/ forage
slide16

Why is > 3 important?

  • Young born and crawl up into pouch
  • Latches on teat for months (breathes!)
  • Can have 2 in pouch, 1 latched, 1 not
  • Different milk in each teat!
slide17

Why is > 3 important?

  • Can have embryo in utero
  • Lactation results in delayed growth
  • Prolactin inhibits luteal function/ P4
  • What a baby machine!!!
marsupials
MARSUPIALS
  • ~ 275 SPECIES!
eutherian
EUTHERIAN
  • > 95 % OF ALL MAMMALS
  • TRUE PLACENTA!
  • Extract nutrients from maternal blood!
  • 21 orders ( see Dr. Anderson paper)
  • Born more mature
  • Lactations from 4 days to years!
future thoughts
FUTURE THOUGHTS
  • What do mammals have in common:

- hair

- mammary glands

* development and tissue

* secretion products

eutherian3
EUTHERIAN

What do boy and girl mammary glands have in common?

slide25

AS 337 LACTATION BIOLOGY

EXTRA CREDIT QUESTION 1 (10 PTS)

Are the SUBCLASSES / orders we talked about in class (monotremes / marsupials/ 21 orders for eutherians) all there or are there some lost subclasses / orders looking for a home? Can you find a lost subclass / order and if so, state what it is and where you found it! (paper or website!) Or any other interesting evolution facts?

DUE ON OR BEFORE CLASS NEXT THURS 1/23

Can give to Mackenzie, Kali, Melissa, Brittany , or me in class or send via email .

HAVE A FANTASTIC WEEKEND!!!

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