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EXPERIMENTAL STUDIES ON EMBRYOGENESIS IN HYDROZOANS (TRACHYLINA AND SIPHONOPHORA) WITH DIRECT DEVELOPMENT.
Biol Bull. 1983 Dec; 165(3):591-618.BB

Abstract

The normal embryology of the trachymedusa Aglantha digitale and the siphonophores Nanomia cara and Muggiaea atlantica is described. Marking experiments on these embryos indicate that the site of first cleavage initiation corresponds to the oral pole of the oral-aboral axis. In Muggiaea the plane of the first cleavage corresponds to the plane of bilateral symmetry. Experiments in which presumptive aboral and oral regions are isolated from these embryos at different stages of development indicate that there is an early determination of different regions along this axis. Only the oral region of the Muggiaea embryo has the ability to regulate. These eggs have a pronounced centrolecithal organization. As a consequence of cleavage, the outer ectoplasmic layer of the egg ends up in the cells that form the ectoderm, while the inner or endoplasmic region of the egg ends up in the cells that form the endoderm. Experimentally created fragments of fertilized eggs that contain only ectoplasm differentiate to form an unorganized ectodermal cell mass, indicating that endoplasm is necessary in order to differentiate endoderm. The process of embryogenesis in these animals and the developmental mechanisms they use are very different from those used by hydrozoans with indirect development. These embryos use a suite of developmental mechanisms which are very similar to those used by ctenophores. The significance of this similarity is discussed.

Authors

No affiliation info available

Pub Type(s)

Journal Article

Language

eng

PubMed ID

29324014

Citation

Freeman, Gary. "EXPERIMENTAL STUDIES ON EMBRYOGENESIS in HYDROZOANS (TRACHYLINA and SIPHONOPHORA) WITH DIRECT DEVELOPMENT." The Biological Bulletin, vol. 165, no. 3, 1983, pp. 591-618.
Freeman G. EXPERIMENTAL STUDIES ON EMBRYOGENESIS IN HYDROZOANS (TRACHYLINA AND SIPHONOPHORA) WITH DIRECT DEVELOPMENT. Biol Bull. 1983;165(3):591-618.
Freeman, G. (1983). EXPERIMENTAL STUDIES ON EMBRYOGENESIS IN HYDROZOANS (TRACHYLINA AND SIPHONOPHORA) WITH DIRECT DEVELOPMENT. The Biological Bulletin, 165(3), 591-618. https://doi.org/10.2307/1541468
Freeman G. EXPERIMENTAL STUDIES ON EMBRYOGENESIS in HYDROZOANS (TRACHYLINA and SIPHONOPHORA) WITH DIRECT DEVELOPMENT. Biol Bull. 1983;165(3):591-618. PubMed PMID: 29324014.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - EXPERIMENTAL STUDIES ON EMBRYOGENESIS IN HYDROZOANS (TRACHYLINA AND SIPHONOPHORA) WITH DIRECT DEVELOPMENT. A1 - Freeman,Gary, PY - 2018/1/12/entrez PY - 1983/12/1/pubmed PY - 1983/12/1/medline SP - 591 EP - 618 JF - The Biological bulletin JO - Biol. Bull. VL - 165 IS - 3 N2 - The normal embryology of the trachymedusa Aglantha digitale and the siphonophores Nanomia cara and Muggiaea atlantica is described. Marking experiments on these embryos indicate that the site of first cleavage initiation corresponds to the oral pole of the oral-aboral axis. In Muggiaea the plane of the first cleavage corresponds to the plane of bilateral symmetry. Experiments in which presumptive aboral and oral regions are isolated from these embryos at different stages of development indicate that there is an early determination of different regions along this axis. Only the oral region of the Muggiaea embryo has the ability to regulate. These eggs have a pronounced centrolecithal organization. As a consequence of cleavage, the outer ectoplasmic layer of the egg ends up in the cells that form the ectoderm, while the inner or endoplasmic region of the egg ends up in the cells that form the endoderm. Experimentally created fragments of fertilized eggs that contain only ectoplasm differentiate to form an unorganized ectodermal cell mass, indicating that endoplasm is necessary in order to differentiate endoderm. The process of embryogenesis in these animals and the developmental mechanisms they use are very different from those used by hydrozoans with indirect development. These embryos use a suite of developmental mechanisms which are very similar to those used by ctenophores. The significance of this similarity is discussed. SN - 1939-8697 UR - https://www.unboundmedicine.com/medline/citation/29324014/EXPERIMENTAL_STUDIES_ON_EMBRYOGENESIS_IN_HYDROZOANS_(TRACHYLINA_AND_SIPHONOPHORA)_WITH_DIRECT_DEVELOPMENT L2 - https://doi.org/10.2307/1541468 DB - PRIME DP - Unbound Medicine ER -
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