LARVAL SPICULES, CILIA, AND SYMMETRY AS REMNANTS OF INDIRECT DEVELOPMENT IN THE DIRECT-DEVELOPING SEA-URCHIN HELIOCIDARIS-ERYTHROGRAMMA
LARVAL SPICULES, CILIA, AND SYMMETRY AS REMNANTS OF INDIRECT DEVELOPMENT IN THE DIRECT-DEVELOPING SEA-URCHIN HELIOCIDARIS-ERYTHROGRAMMA
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DOI：
10.1006/dbio.1995.1037
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发表时间：
1995-02-01
影响因子：
2.7
通讯作者：
EMLET, RB
中科院分区：
文献类型：
--
作者：
EMLET, RB
非饲养幼虫的海胆Heliocidaris erythrogramma提出的文化和研究的表达幼虫骨架和纤毛带的安排。将不透明幼虫固定、清除，并在偏振光下检查钙化证据。受精后35小时（22 ℃），一对三辐状骨针出现在幼虫的后端。这对的每一个成员形成一个有孔骨针，因为它横向生长。这对和另一对随后形成的，被安排在一个平面的双边对称正交的少年口头aboral轴。这些成对的幼虫骨针可以被鉴定为在plutei中发现的减少的口后和背后杆的表达，并且它们的表达表明H.红纹幼虫在左侧形成，幼虫体轴在这种修改的幼虫中是保守的。到44小时，纤毛带形成为一个不完整的横向环的三个部分的后端和背面的卵形幼虫。这些片段中的纤毛长到45-50 μ m的长度，比其他报道的棘皮动物幼虫的游泳和进食纤毛长。带节被解释为肩章（专门游泳带）的表达，而不是pluteus的进食纤毛带。纤毛带段和幼虫骨针都是双边对称的，相对于同一平面，并表示保守的幼虫双边对称性，尽管主要的不对称的命运细胞两侧的这一平面上的青少年发展的贡献。(C)出版社：Academic Press
Nonfeeding larvae of the echinoid Heliocidaris erythrogramma were raised in culture and examined for expression of a larval skeleton and for the arrangement of the ciliated band. Opaque larvae were fixed, cleared, and examined under polarized light for evidence of calcification. By 35 hr after fertilization (at 22 degrees C), a pair of triradiate spicules was present at the posterior end of the larvae. Each member of this pair formed a fenestrated spicule as it grew laterally. This pair and another pair which formed subsequently, were arranged across a plane of bilateral symmetry orthagonal to the juvenile oral aboral axis. These paired larval spicules can be identified as reduced expressions of postoral and posterodorsal rods found in plutei, and their expression indicates that the juvenile rudiment of H. erythrogramma forms on the left side and that larval body axes are conserved in this modified larva. By 44 hr the ciliated band formed as an incomplete transverse loop of three segments at the posterior end and on the dorsal surface of the ovoid larva. Cilia in these segments grew to lengths of 45-50 mu m, longer than other swimming and feeding cilia reported for echinoderm larvae. Band segments are interpreted as expressions of epaulettes (specialized swimming bands) rather than the feeding ciliated band of the pluteus. The ciliated band segments and the larval spicules are both bilaterally symmetrical with respect to the same plane and indicate conserved larval bilateral symmetry despite the major asymmetry of the fates of cells on either side of this plane in their contribution to juvenile development. (C) 1995 Academic Press, Inc.