{"title":"ESCAPE PROCESSES IN EMBRYOS OF DICYEMIDS (PHYLUM DICYEMIDA).","authors":"Naoki Hisayama, Hidetaka Furuya","doi":"10.1645/23-30","DOIUrl":null,"url":null,"abstract":"<p><p>Dicyemid mesozoans usually consist of 10 to 40 cells. They are characterized by 2 distinct embryos, vermiform and infusoriform, that develop within the axial cell of the adult. The means of escape of each embryo from the parent body was studied in Dicyema japonicum and Dicyema misakiense, parasites of Octopus sinensis. There were no differences in means of escape between species or embryo type, apparently due to morphological constraints whereby the parents (nematogen or rhombogen) share a similar body organization. Escapes were effected through the gap between adjacent peripheral cells of the adult, rupturing the axial cell membrane and the membrane that envelopes the embryo. After the embryo escaped, the path was closed by the enveloping membrane left behind by the embryo. Vermiform embryos can escape from any region of the body, although more embryos were observed to escape from anterior regions than from posterior regions. Infusoriform embryos escaped from both anterior and posterior regions in the axial cell, with more embryos observed to escape from the posterior regions. The different escape regions for the 2 types of embryo are presumably related to the adult body plan lacking a genital opening, so each different type of embryo has its appropriate site of escape.</p>","PeriodicalId":16659,"journal":{"name":"Journal of Parasitology","volume":null,"pages":null},"PeriodicalIF":1.0000,"publicationDate":"2023-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Journal of Parasitology","FirstCategoryId":"3","ListUrlMain":"https://doi.org/10.1645/23-30","RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q4","JCRName":"PARASITOLOGY","Score":null,"Total":0}
引用次数: 0
Abstract
Dicyemid mesozoans usually consist of 10 to 40 cells. They are characterized by 2 distinct embryos, vermiform and infusoriform, that develop within the axial cell of the adult. The means of escape of each embryo from the parent body was studied in Dicyema japonicum and Dicyema misakiense, parasites of Octopus sinensis. There were no differences in means of escape between species or embryo type, apparently due to morphological constraints whereby the parents (nematogen or rhombogen) share a similar body organization. Escapes were effected through the gap between adjacent peripheral cells of the adult, rupturing the axial cell membrane and the membrane that envelopes the embryo. After the embryo escaped, the path was closed by the enveloping membrane left behind by the embryo. Vermiform embryos can escape from any region of the body, although more embryos were observed to escape from anterior regions than from posterior regions. Infusoriform embryos escaped from both anterior and posterior regions in the axial cell, with more embryos observed to escape from the posterior regions. The different escape regions for the 2 types of embryo are presumably related to the adult body plan lacking a genital opening, so each different type of embryo has its appropriate site of escape.
期刊介绍:
The Journal of Parasitology is the official peer-reviewed journal of the American Society of Parasitologists (ASP). The journal publishes original research covering helminths, protozoa, and other parasitic organisms and serves scientific professionals in microbiology, immunology, veterinary science, pathology, and public health. Journal content includes original research articles, brief research notes, announcements of the Society, and book reviews. Articles are subdivided by topic for ease of reference and range from behavior and pathogenesis to systematics and epidemiology. The journal is published continuously online with one full volume printed at the end of each year.