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EVOLUTION OF THE MAMMARY GLAND AND SECRETIONS Why is the mammary gland really a gland of reproduction?

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Presentation on theme: "EVOLUTION OF THE MAMMARY GLAND AND SECRETIONS Why is the mammary gland really a gland of reproduction?"— Presentation transcript:

1 EVOLUTION OF THE MAMMARY GLAND AND SECRETIONS Why is the mammary gland really a gland of reproduction?

2 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!

3 GIVE A 1 WORD DEFINITION FOR THIS COURSE! MAMMALS!

4 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)!

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6 MAMMALS WHAT ARE 2 DISTINCT FEATURES OF MAMMALS? HAIR? MAMMARY GLANDS!

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8 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

9 Duckbill Platypus

10 Mammary gland: no teats tubules myoepitelial cells milk forced onto hair

11 Female lays eggs 2 weeks post mating day incubation period 1-2 eggs Young: 350 mg at birth; 3-4 mo.- 1/2 adult wt.

12 WHY MAMMALS? WHY MAMMARY GLANDS? Protect egg! Less young but better survival! Nourish young!

13 ECHIDNA Lay eggs but transfer to temp. brood pouch 10 day incubation 3-4 month lactation special areas called areola in pouch: tubules

14 SUBCLASS: THERIA HAVE PLACENTA!

15 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

16 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!

17 Why is > 3 important? Can have embryo in utero Lactation results in delayed growth Prolactin inhibits luteal function/ P4 What a baby machine!!!

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19 MARSUPIALS ~ 275 SPECIES!

20 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!

21 EUTHERIAN

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23 FUTURE THOUGHTS What do mammals have in common: - hair - mammary glands * development and tissue * secretion products

24 EUTHERIAN What do boy and girl mammary glands have in common?

25 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 . HAVE A FANTASTIC WEEKEND!!!


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