11 14 07 - Reproductive System III

11 14 07 - Reproductive System III - Chapter 21 The...

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Chapter 21 – The Reproductive System III Female reproductive system, continued. Mammals – three major groups that are defined by differences in female reproductive system 1) Prototherians (Monotreme:s meaning one hole/ cloaca ): Echidnas and platypus Have a cloaca Oviparous. Eggs travel down the oviduct and have secondary layers added to them, which provide further nourishment. The oviducts fuse before entering the cloaca Egg is ovulated and amniotic addition through oviduct There is a uterus at end of oviduct before fusion of two oviducts Fertilization and development begin while in the oviduct; once laid the eggs are placed in a pouch (echidnas, not platypi) After hatching, the young feed on milk secreted by the mother through milk glands – no nipples Born at very end of organogenesis Platypus Electro receptors in bills Semi aquatic Echinda Has a pouch Has macrolecithal eggs Offspring born in very young(embryonic-like) state Develop in pouch Don’t have completely developed mammary glands Do have specialized glands in pouch for milk excretion 2) Metathericans (half beast) (Marsupials): Viviparous. Marsupials do not have a cloaca; the digestive system has its own exit, the rectum. The
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11 14 07 - Reproductive System III - Chapter 21 The...

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