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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. 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

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  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)!

  5. MAMMALS • WHAT ARE 2 DISTINCT FEATURES OF MAMMALS? • HAIR? • MAMMARY GLANDS!

  6. 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

  7. Duckbill Platypus

  8. Mammary gland: • no teats • tubules • myoepitelial cells • milk forced onto hair

  9. 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.

  10. WHY MAMMALS? Less young but better survival! • Protect egg! Nourish young! WHY MAMMARY GLANDS?

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

  12. SUBCLASS: THERIA HAVE PLACENTA!

  13. 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

  14. 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!

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

  16. MARSUPIALS • ~ 275 SPECIES!

  17. 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!

  18. EUTHERIAN

  19. EUTHERIAN

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

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

  22. 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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