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A coelom, or body cavity, contains major organs. It has two openings, one for the input of food and another for the release of waste, and is filled with lubricant. All Bilateria have a coelom, but are divided into two groups depending on whether the first coelom to develop turns into an anus or a mouth, which are classified as Deuterostomes and Chordates respectively.
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Incorrect.
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In animals of the phyla Annelida, Mollusca, and Arthropoda, the mesoderm forms as a mass of tissue from special embryonic cells between an outer layer, the ectoderm, and an inner layer, the endoderm. The coelom then forms as a result of the splitting and hollowing out of the mesodermal mass. In animals of the phyla Echinodermata and Chordata, the mesoderm arises as the lining of folds developing from the endoderm, and the spaces within these folds form the coelom. The structure of the embryonic coelom is relatively simple; in an adult other organs push into the coelomic cavity, and it is also subdivided into compartments, e.g., the pericardial cavity, in which the heart develops.
...FTW? |
Your browser skills bring you ever closer, but you haven't answered the actual question I asked. :p
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A coelom is a cavity lined by an epithelium derived from mesenchyme. Organs formed inside a coelom can freely move, grow, and develop independently of the body wall while fluid cushions and protects them from shocks. This key innovation evolved hundreds of millions of years ago and led to the evolution of nearly all large, complex animals.
Arthropods and mollusks have a reduced (but still true) coelom. Their principal body cavity is the hemocoel of an open circulatory system. Mammalian embryos develop two coelomic cavities: the intraembryonic coelom and the extraembryonic coelom (or chorionic cavity). The intraembryonic coelom is lined by somatic and splanchnic lateral plate mesoderm, while the extraembryonic coelom is lined by extraembryonic mesoderm. The intraembryonic coelom is the only cavity that persists in the mammal at term, which is why its name is often contracted to simply coelomic cavity. Subdividing the coelomic cavity into compartments, for example, the pericardial cavity, where the heart develops, simplifies discussion of the anatomies of complex animals. |
Incorrect, and to recap the question: I am asking the name of the two types of coelomic formation in all coelomates, and how those two types are different from each other (otherwise there would only be one type of coelomic formation).
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Enterocoelous development of the coelom occurs in deuterostomes. The mesoderm, and coelom, initially develop as pouches off of the primitive digestive tract (the archenteron).
Schizocoelous development of the coelom occurs in protostomes. The mesoderm, and coelom, initially develop from a solid block of mesoderm tissue that develops a split down the middle |
100% correct, point and question to Axl (damn, so close).
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Yay! :D
------------------------ Now for a query which may be easy... i dunno Name a combination of yugioh cards which can net you a first-turn win. *Sans Exodia 5-Card Draw* *First-turn win means that you win either on your beginning the game or your opponent's first draw* I think that's clear enough... |
Quote:
The Wandering God |
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