Blastopore(redirected from Protostoma)
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(also protostomatic mouth, or gastropore), an opening by means of which the cavity of an animal embryo (in the gastrula stage) interacts with the surrounding environment. In the process of development among some animals (protostomatic), the blastopore becomes a mouth or forms both a mouth and an anal opening; in others (deuterostomatic) an anal opening or nerve intestinal canal is formed in place of the blastopore. This temporarily connects the digestive cavity with the cavity of the nerve tract.