Pharyngula

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This article is about the stage in embryonic development. For the science blog by PZ Myers, see Pharyngula (blog).

Pharyngula is the name of a stage in embryonic development. ^[1]

The embryonic development of all vertebrates shows remarkable similarities at the embryonic stage called the pharyngula. At this stage they all contain a:

notochord
dorsal hollow nerve cord
post-anal tail, and
a series of paired branchial grooves.

The branchial grooves are matched on the inside by a series of paired gill pouches. In fishes, the pouches and grooves eventually meet and form the gill slits, which allow water to pass from the pharynx over the gills and out the body.

In the other vertebrates, the grooves and pouches disappear. In humans, the chief trace of their existence is the eustachian tube and auditory canal which (interrupted only by the eardrum) connect the pharynx with the outside of the head.