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The opening of the archenteron.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.



(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.

The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.
References in periodicals archive ?
In contrast to BLASTp comparisons that suggested that Melibe PERIOD was more similar to Mus than Drosophila (Supplementary Table 3, available online), phylogenetic analysis suggested that molluscan PERIOD proteins shared a common ancestor more recently with protostomes other than chordates (Fig.
Hox genes in brachiopods and priapulids and protostome evolution.
Endoplasmic reticulum reorganizations and [Ca.sup.2+] signaling in maturing and fertilized oocytes of marine protostome worms: the roles of MAPKs and MPF.
Past this point, several key features of Owenia's development diverge from the protostome stereotype.
Hb-like expression patterns obtained from other protostome lineages have suggested that the gap function may be restricted to arthropods.
To determine whether the ECM proteins apparently missing from Nematostella might be exclusive to deuterostomes or vertebrates, we used tBLASTn to search for them in protostome genomes (Table 7).
The central nervous system in deuterostomes lies on the dorsal side, but on the ventral side in protostomes, such as the lobster.
Studies using transcriptomic data of a dicyemid, Dicyema japonicum, have also suggested that orthonectids are protostomes (Lu et al, 2017); and another analysis on mitochondrial genomes and nuclear genes suggested that orthonectids are members of the phylum Annelida (Schiffer et al, 2018).
The former belongs to the deuterostomes and the latter to the protostomes, respectively.
While it has been variously suggested that deuterostomes (Nursall, 1962), protostomes (Inglis, 1985), and cnidarians (Hanson, 1977) independently evolved multicellularity, the group most commonly considered to have been derived from a separate protist lineage is the sponges, phylum Porifera (as evidenced by Barnes, 1980, p.
(198) Further investigation on the diversity of flagella and cilia in the future using well-known species or those newly found, such as loss of motile cilia in plants or a certain group of protostomes and compound cilia or macrocilia in metazoa, should shed new light on the biology of dynein and tubulin.
Bilateral symmetry is found in 3 major clades of animals: the Deuterostomes (which includes vertebrates) and two clades of Protostomes, the Ecdysozoa (which includes arthropods and nematodes) and the Lophotrochozoa (which includes molluscs and annelids).