厚壳贻贝胚胎和早期幼虫神经系统发育的初步研究

采用免疫细胞化学技术和荧光染色技术初步研究了厚壳贻贝胚胎及早期幼虫的神经发育情况以及含有不同类型神经细胞的时空分布.在厚壳贻贝从受精开始至囊胚期的整个胚胎发育过程中,均未发现FMRF酰胺类免疫阳性信号和5-羟色胺免疫阳性信号,神经最初形成于担轮幼虫阶段,出现了FMRF酰胺类免疫阳性信号和5-羟色胺免疫阳性信号,36 hpf时,更多的FMRF酰胺类免疫阳性信号出现在幼虫顶部区域左右两侧,伸出的阳性纤维延伸后形成基底神经纤维,并延伸至正在发育的中足所在区域.在顶端区所有阳性信号中,第一个免疫信号始终处于腹部,位置未发生变化.D形幼虫阶段神经系统的FMRF酰胺类免疫阳性信号分别是顶器官的3个顶部阳性信号、侧部2个阳性信号以及足区形成的2个阳性信号.顶器官中的信号延伸出免疫活性纤维形成基底神经纤维.18 hpf时,第1个5-羟色胺免疫阳性信号出现在早期担轮幼虫的顶器官前端.在早期D形幼虫阶段,阳性信号伸出一个短小的基底神经纤维,并延伸至后来发育成的顶器官神经纤维网部位,42 hpf时,更多5-羟色胺阳性信号细胞出现在顶区域,数量增至2～3个.D形幼虫阶段(48 hpf),5-羟色胺免疫阳性信号数量增至4个,分布于脑神经节的周围,其发出的基底纤维延伸至紧密的顶神经纤维网.

Primary study on neuronal development of the embryo and early larvae of the mussel Mytilus coruscus

In the present study,the development of FMRFamide-,serotonin-containing cells in the mussel Mytilus coruscus was examined using immunocytochemical and histofluorescent techniques.During the embryonic development,no FMRFamide-like immunoreactive(lir)and serotonin-lirsensory cell appeared.Neurogenesis started during the trochophore stage at the apical extreme with the appearance of one FMRFamide-lircell and one serotonin-lir sensory cell.The numbers of FMRFamide-lir cell increased at 36 hours postfertilization(hpf)and appeared on the two sides of apical extreme.Fibres of two lateral FMRFamide-lir apical cells projected posteriorly and reached developing foot.The location of the first FMRFamide-lir apical cells in the most ventral apical region did not change during early development.At 48 hpf,three FMRFamide-lir apical cells,two lateral FMRFamide-lir apical cells and two cells of developing foot appeared.The FMRFamide-lirfibres projected and the basal neuropil formed.The earliest serotonin-lir cell appeared at 18 hpf at the anterior extreme of the apical region of developing apical organ.At 30 hpf and 36 hpf,the serotonin-lir cell extended a short basal fibre into the region of the developing neuropil of the apical organ.The numbers of the serotonin-lir cell increased to 2-3 at 42 hpf and appeared in the apical region of the D-shaped larvae.Four serotonin-lir cells were detected at 48 hpf and these cells projected basal fibres into the compact apical neuropil.