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ALLOMETRIE ET DIFFERENCIATION DES GRANDS PLANS D'ORGANISATION DES METAZOAIRES

机译：大型群落组织计划的异位和分化

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摘要

Though the implications of allometric pattern variations have been outlined in several instances in the divergence between rather minor taxa, little attention has been paid to the major events of diversification of the metazoan clade. The present paper focuses primarily on the protostome-deuterostome divergence and gives some insights into the diversification within the annelid-mollusc-sipunculid clade. In the early stages following gastrulation of deuterostomes, the dorsal part of the ectoderm becomes slightly longer than the ventral one, driving the blastopore to a ventral position very close to the posterior end of the body. The endoderm is thus constrained to grow towards the anterior end, in the vicinity of which it forms its second opening which, owing to its position, becomes the mouth (fig. 1). In annelids, which may be considered as nearly archetypal protostomes, the derivatives of 2d and 3d blastomeres (i.e. a part of dorsal ectoderm) invade the posterior pole of the embryo by means of a very strong positive allometry. Thus brings the dorsal blastopo-ral lip into a posteroventral position, blocking a large part of the elongated blastopore, in which the communication with the archenteron is restricted to the most anterior part, thus differentiating into a mouth (fig. 2). The second aperture of the archenteron is constrained to be posterior, thus becoming the anus. It is generally admitted that the anus opens at the posterior end of the virtual blastopore, but this opinion is no longer supported when taking into account the dorsal origin (2d-3d) of proctodeum and of some components, such as ectoteloblasts or telotrochoblasts, of the so-called ventral ectoderm (DORRESTEJN et al, 1993), and it is more likely that the anus of protostomes is independent of the blastopore.
机译：尽管在某些情况下在相当小的分类单元之间的差异中概述了异速异体模式变化的含义，但对后生进化枝多样性的主要事件却鲜有关注。本文主要侧重于原生动物组-氘代动物组的差异，并提供了对类腔动物-软体动物-刺状进化枝内的多样化的一些见解。在氘化子宫口胃化后的早期，外胚层的背侧部分变得比腹侧稍长，从而将胚孔驱动到非常靠近人体后端的腹侧位置。因此，内胚层被限制向前端生长，在其附近形成其第二个开口，由于其位置，它变成了嘴（图1）。在可以被认为是近乎原型的前肢动物中，2d和3d卵裂球的衍生物（即背外胚层的一部分）通过非常强的正向异构性侵入胚胎的后极。因此，使胚盘背唇进入后腹位置，阻塞了细长的胚孔的很大一部分，其中与原肠的连通仅限于最前部分，从而分化为嘴巴（图2）。原肠的第二孔被限制在后方，从而成为肛门。通常认为肛门在虚拟胚孔的后端开口，但是考虑到直肠的直肠原位和某些成分（例如外胚层细胞或成纤维细胞）的背面起源（2d-3d），这种观点不再得到支持。所谓的腹外胚层（DORRESTEJN等，1993），并且原虫的肛门更可能与胚泡无关。

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  • 来源
    《Bulletin de la Societe Zoologique de France》 |2002年第1期|p.11-23|共13页
  • 作者

    Jean GENERMONT;

  • 作者单位

    UPRES-A 8079 "Ecologie, Systematique et Evolution" Institut de Biologie animale integrative et cellulaire Batiment 446, Universite de Pairs-Sud 91405 Orsay Cedex France;

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  • 正文语种 fre
  • 中图分类 动物学;
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