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Development of in vitro fertilized embryos of the polyclad flatworm,Hoploplana inquilina,following blastomere separation and deletion 总被引:1,自引:0,他引:1
Barbara Conta Boyer 《Development genes and evolution》1987,196(3):158-164
Summary After in vitro fertilization of naked eggs of the polyclad turbellarian, Hoploplana inquilina, both cell separation experiments and deletions of specific blastomeres are possible. With these techniques one can analyze the developmental potential of isolated blastomeres and determine if the embryonic axes have been established at the four-cell stage in this primitive, equally-cleaving spiralian embryo. Two-cell separation experiments with development of both halves resulted in pairs of larvae 1) neither of which had an eye (29%), 2) both of which had one eye (19%), and 3) one of which was eyeless and the other was one-eyed (43%). Deletion of one blastomere at the four-cell stage resulted in 68% one-eyed, 28% two-eyed and 3% eyeless larvae. The one-eyed larvae were asymmetric with respect to eye position with more having right than left eyes. Abnormal or missing ventrolateral lobes occurred with deletion of any of the macromeres at four cells but were significantly more common when A or C rather than B or D was deleted. The experiments support the hypothesis that eye development is a consequence of cytoplasmic localization of both a specific eye precursor and an inducer which segregate independently of cleavage planes, and indicate that the embryonic axes have been determined at the four-cell stage. 相似文献
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多肠目薄背涡虫的胚胎发育 总被引:1,自引:1,他引:0
薄背涡虫(Notoplana humilis)的产卵高峰期在春末夏初。胚胎发育为螺旋式卵裂、外包法形成原肠胚,以大卵裂球储存卵黄。14~16℃下约20d左右幼虫由卵膜中孵化,但不是典型的牟勒氏幼虫。幼虫经历一周左右的浮游生活和两周左右的底栖生活后,逐渐发育为涡虫幼体。 相似文献
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