Clonal domains in postlarval Platynereis dumerilii (Annelida: Polychaeta)
Clonal domains in postlarval Platynereis dumerilii (Annelida: Polychaeta)
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DOI：
10.1002/jmor.10375
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发表时间：
2005-12-01
影响因子：
1.5
通讯作者：
Fischer, A
中科院分区：
文献类型：
--
作者：
Ackermann, C;Dorresteijn, A;Fischer, A
在用于软化卵包膜的酶促程序之后，向多毛类动物Platynereis dumerilii的胚胎中的卵裂球注射TRITC-葡聚糖。在以下卵裂球中注射成功：AB、CD、A、B、C、D、1a-1d、1A-1D、4d和4d（1）。荧光标记的分布记录通过共聚焦激光扫描显微镜的年轻的，三节蠕虫后3或4天的发展，在某些情况下，也在1天大担轮幼虫。通过单个光学切片、通过堆叠有限数量或完整的光学切片组以及通过计算机生成的标记组织域和整个蠕虫的完整图像堆栈的身体轮廓的表面视图来记录结果。关于它们从胚胎细胞模式的起源，可以区分出五个主要的区室，它们共同组成了幼虫的身体：1）头部的外表皮、表皮和神经区，由四个区域组成，这些区域排列成准放射状，分别来自于微粒1a、1b（左腹侧和右腹侧）以及1c和1d（右背侧和左背侧）。2)一个起源于小孢子2a（1）-2c（1）的头部的轮后表皮区域，构成头部的腹侧和侧部轮后表皮。3)头部的口胚-外胚层区域，包括口胚（小孢子2a（2）和2c（2））、中胚层包膜和头部中胚层（小孢子3a-3d）。4)由四个末端大单体4A-4D组成的实心圆锥体，作为内胚层原基形成树干的核心。5)躯干的表皮和中胚层覆盖层起源于背侧小孢子2d和4d。所谓的（第一，前）口缘纤毛在头的后侧的区域也由2D和4D衍生的躯干组织，从而证实了假设的下降，该地区及其附属物从头部化的前躯干段和它的伪足。第一和第三微粒层的细胞谱系域排列在矢状面的左侧或右侧，而第二四重体的两个微粒在侧面，最初，两个在中间位置（2b腹侧和2d背侧）。2d细胞的后代从背侧位置向腹侧中线扩展，4d细胞的后代从后背侧位置向前侧扩展，最初形成两个侧带。在头的外胚层部分，来自小节1a和1b的神经外胚层组织的一部分交织在一个中胚层条中，所有四个象限（1a-1d）的第一个小节后代的一部分联合收割机结合形成一个中央脑神经元。后者的每一个都通过两个食管周围的连接发送神经突。成对的肌肉束穿过头部延伸到触角的基部，可能来自于3a和3b。口道的中胚层被膜。很可能是由3c和3d微粒组成的。本文讨论了杜氏扁虫胚胎和成虫体轴对称性的形成和体轴的性质。
Following an enzymatic procedure for softening the egg envelope, blastomeres in the embryo of the polychaete Platynereis dumerilii were injected with TRITC-dextran. Injection was successful in the following blastomeres: AB, CD, A, B, C, D, 1a-1d, 1A-1D, 4d, and 4d(1). The distribution of fluorescent label was recorded by confocal laser scanning microscopy of young, three-segmented worms after 3 or 4 days of development, in some cases also in 1-day-old trochophore larvae. Results were documented by single optical sections, by stacking a limited number or a complete set of optical sections, and by computer-generated surface views of both the labeled tissue domains and the body contours from complete image stacks of whole worms. With respect to their descent from the embryonic cell pattern, five major compartments can be distinguished which together compose the body of the young worm: 1) The epispheric, epidermal, and neural region of the head, composed of four domains arranged as quasi-radial sectors derived from micromeres 1a, 1b (left and right ventral), and 1c and 1d (right and left dorsal). 2) A posttrochal epidermal region of the head originating from micromeres 2a(1)-2c(1) and constituting the ventral and lateral posttrochal epidermis of the head. 3) A stomodeal-ectomesodermal region of the head, including the stomodeum (micromeres 2a(2) and 2c(2)), its mesodermal envelope, and head mesoderm (micromeres 3a-3d). 4) A solid cone composed of the four terminal macromeres 4A-4D, forming the core of the trunk as the endoderm anlage. 5) An epidermal and mesodermal coating of the trunk originating from the dorsal micromeres 2d and 4d. The region of the so-called (first, anterior) peristomial cirri at the posterior flanks of the head is also composed of 2d- and 4d-derived trunk tissue, thus corroborating the postulated descent of this region and its appendages from a cephalized anteriormost trunk segment and its parapodia. The cell-lineage domains of the first and third micromere tiers are arranged left or right of the sagittal plane, while two micromeres of the second quartet are in a lateral and, initially, two in a median position (2b ventral and 2d dorsal). The offspring of micromere 2d expand from a dorsal position toward the ventral midline and those of cell 4d from a posterior-dorsal site toward the anterior, initially forming two lateral bands. In the epispheric part of the head, part of the neurectodermal tissue derived from micromeres 1a and 1b interweaves in a mediosagittal bar, and part of the first micromere offspring of all four quadrants (1a-1d) combine in forming a central brain neuropil. Each of the latter sends neurites through both of the circumesophageal connectives. Paired muscle tracts extend through the head toward the base of the antennae and are probably derived from micromeres 3a and 3b. A mesodermal envelope of the stomodeum. is probably built by the 3c and 3d micromeres. The formation of symmetry and the nature of the body axes in the embryo and adult of Platynereis dumerilii are discussed.