Studies on dwarf larvae developed from isolated blastomeres of the starfish. Asterina pectinifera.
نویسندگان
چکیده
Not only a whole denuded egg, but also blastomeres isolated from 2-, 4- and 8-cell starfish embryos developed into morphologically normal, but dwarf bipinnariae, the sizes of which were roughly proportionate to that of the respective original blastomeres. Some of the blastomeres isolated from the 16-cell stage were also capable of developing into the larval stage. All isolated blastomeres divided in good synchrony with the control embryos. Blastulae of all groups gastrulated within quite a short range of time, around 14-5 h after insemination at 20+/-1 degrees C, although one-third of the 1/8-blastula missed this chance but gastrulated by 19.5 h. The number of constituent cells of the 1/8-gastrula was counted to be about 560, which corresponds roughly to one-half that of the 1/4-, one-fourth of the 1/2- and one-eight of the 1/1-gastrula. This ratio also fitted roughly for the total cell volume. The results are compared with those of other invertebrate species, as well as of some vertebrates, and are discussed in connexion not only with the concepts of 'regulative' and 'mosaic' eggs, but also with a criterion that does not fit into either of these; the developmental system of the mammals.
منابع مشابه
Establishment of embryonic axes in larvae of the starfish, Asterina pectinifera.
In order to clarify the relationships between the first cleavage plane and the embryonic axes, early cleavage pattern of the fertilized eggs of the starfish. Asterina pectinifera was reexamined. It was ascertained that the polar bodies were formed at the site to which the germinal vesicle had closely located before the initiation of the meiotic division, and that the first cleavage plane passed...
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ورودعنوان ژورنال:
- Journal of embryology and experimental morphology
دوره 46 شماره
صفحات -
تاریخ انتشار 1978