Presentation on theme: "EVOLUTION OF THE MAMMARY GLAND AND SECRETIONS Why is the mammary gland really a gland of reproduction?"— Presentation transcript:
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!! Huge female expenditure for something outside their own body! Develop offspring/ species survival!
GIVE A 1 WORD DEFINITION FOR THIS COURSE! 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)!
MAMMALS WHAT ARE 2 DISTINCT FEATURES OF MAMMALS? HAIR? MAMMARY GLANDS!
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
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.
WHY MAMMALS? WHY MAMMARY GLANDS? Protect egg! Less young but better survival! Nourish young!
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 HAVE PLACENTA!
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
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!
Why is > 3 important? Can have embryo in utero Lactation results in delayed growth Prolactin inhibits luteal function/ P4 What a baby machine!!!
MARSUPIALS ~ 275 SPECIES!
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 What do mammals have in common: - hair - mammary glands * development and tissue * secretion products
EUTHERIAN What do boy and girl mammary glands have in common?
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!!!