ZOL - DEVELOPMENT forms from archenteron at each end ectodermal invagination Anterior end stomodaeum(part that is going to become the mouth lined

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DEVELOPMENT - forms from archenteron - at each end – ectodermal invagination Anterior end – stomodaeum (part that is going to become the mouth) – lined with ectoderm Posterior end – blastopore becomes the anus - proctodaeum lined with ectoderm - fuses with endoderm of gut cloaca Pharynx differentiates from the archenteron. - forms outpouchings that form between visceral arches - pharyngeal pouches – met by ectodermal invagination from exterior - first pouch – either reduced to spiracle or lost - rest – form branchial chambers that contain gills in fish Fish – pharynx is large Tetrapods – pharynx is quite short Connects oral cavity and esophagus. Pouches form during development (4 pouches, not all 6). 1 st becomes the auditory or the eustacian tube – middle ear cavity. Parathyroids (calcium ions balance), thymus and tonsils (both immune system) all form from the walls of the pouches. Outpouchings of the gut form many internal organs. e.g. thyoid gland, lungs, liver, pancreas, urinary bladder (allantois) Gut basically consists of a tube that runs through an organism. - ectoderm at each end - long stretch of endoderm in between - endoderm forms inner layer - mucosa - surrounded by muscle (smooth muscle peristalsis), connective tissue - serosa
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This note was uploaded on 06/29/2008 for the course ZOL 328 taught by Professor Hill during the Spring '08 term at Michigan State University.

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ZOL - DEVELOPMENT forms from archenteron at each end ectodermal invagination Anterior end stomodaeum(part that is going to become the mouth lined

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