Larval development in the Homoscleromorpha (Porifera, Demospongiae)
Larval development in the Homoscleromorpha (Porifera, Demospongiae)
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DOI：
10.1111/j.1744-7410.2003.tb00084.x
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发表时间：
2003-01-01
影响因子：
1.2
通讯作者：
Tokina, D
中科院分区：
文献类型：
--
作者：
Boury-Esnault, N;Ereskovsky, A;Tokina, D
对8种地中海同骨海绵类物种从有腔囊胚到完全发育的幼虫的胚胎发育进行了研究，这8个物种分别是：叶状奥斯科海绵（Oscarella lobularis）、结节奥斯科海绵（O. tuberculata）、微叶奥斯科海绵（O. microlobata）、帝王奥斯科海绵（O. imperialis）、三叶扁海绵（Plakino trilopha）、亚尼扁海绵（P. jani）、烛台皮海绵（Corticium candelabrum）和贾氏假皮海绵（Pseudocorticium jarrei）。所有这些物种的幼虫形态发生过程相似；然而，奥斯科海绵属的物种比扁海绵属和烛台皮海绵的细胞增殖更为活跃。细胞分裂的结果是形成一种有褶皱、具鞭毛的幼虫，称为环囊胚。它由极化的单鞭毛细胞构成的柱状上皮组成，其中散布着一些无鞭毛的卵形细胞。中央腔总是含有共生细菌。在叶状奥斯科海绵、帝王奥斯科海绵和贾氏扁海绵中还存在母体细胞。在完全发育的幼虫中，每个物种的细胞形状和大小是恒定的。前极的细胞有含有异质物质的大液泡；后外侧区的细胞有核内类晶状内含物；后极的鞭毛细胞有大的嗜锇内含物。细胞间连接连接着细胞的顶端部分，其下方是其他特化的细胞连接。位于鞭毛细胞下方的基膜衬于幼虫腔。这是在多孔动物幼虫中首次观察到基膜。鞭毛细胞的基部装置的特征是在基体正下方有一个副中心粒。单个基根丝是横纹状的。同骨海绵类幼虫中存在基膜和真正的上皮——这在多孔动物分支中是独特的，且与真后生动物相同——这表明寻常海绵纲可能是并系的。
Embryonic development from coeloblastula to fully developed larva was investigated in 8 Mediterranean homoscleromorph species: Oscarella lobularis, O. tuberculata, O. microlobata, O. imperialis, Plakino trilopha, P. jani, Corticium candelabrum, and Pseudocorticium jarrei. Morphogenesis of the larva is similar in all these species; however, cell proliferation is more active in species of Oscarella than in Plakina and C. candelabrum. The result of cell division is a wrinkled, flagellated larva, called a cinctoblastula. It is composed of a columnar epithelium of polarized, monoflagellated cells among which are scattered a few non-flagellated ovoid cells. The central cavity always contains symbiotic bacteria. Maternal cells are also present in O. lobularis, O. imperialis, and P. Jarrei. In the fully developed larva, cell shape and dimensions are constant for each species. The cells of the anterior pole have large vacuoles with heterogeneous material; those of the postero-lateral zone have an intranuclear paracrystalline inclusion; and the flagellated cells of the posterior pole have large osmiophilic inclusions. Intercellular junctions join the apical parts of the cells, beneath which are other specialized cell junctions. A basement membrane underlying the flagellated cells lines the larval cavity. This is the first observation of a basement membrane in a poriferan larva. The basal apparatus of flagellated cells is characterized by an accessory centriole located exactly beneath the basal body. The single basal rootlet is cross striated. The presence of a basement membrane and a true epithelium in the larva of Homoscleromorpha-unique among poriferan clades and shared with Eumetazoa-suggests that Demospongiae could be paraphyletic.