Introductory Anatomy: Excretory & Reproductive Systems During the process of evolution we quite often find that structures evolved to do one thing are no longer relevant. The appendix is a good example: useful in animals feeding on grass it has no function in man, has become small and may ultimately disappear. In other cases these relict organs may be taken over for quite another purpose. This is the case with the excretory and reproductive systems which are anatomically and evolutionary linked, and where parts of the excretory system have been taken over by the reproductive system. To understand this we must go back to our coelomate ancestor. Remember this had a gut and a coelom lined with thin mesothelium. Now a large cavity with a thin wall like this is ideal for dumping waste, and it seems that the coelom was so used. The result, of course is that it would gradually fill with ions, salts, water and what have you. This seems to have been countered by forming paired lateral ducts, lined with cilia and called
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This note was uploaded on 11/08/2011 for the course BIOLOGY BSC1086L taught by Professor Leostouder during the Fall '10 term at Broward College.