We examined the morphology of fertilized egg and ultrastructures of fertilized egg envelopes of dwarf rainbowfish (Melanotaenia praecox) belong to Melanotaeniidae using light and electron microscopes. The fertilized eggs were spherical with adhesive filament, transparent, demersal, and had a narrow perivitelline space and small oil droplets. The size of fertilized egg was 1.02 ± 0.18 mm (n = 30), and there were two kinds of adhesive filament on the fertilized eggs. The long and thick (diameter 12.22 ± 0.52 μm, n = 20) adhesive filaments were only at the area of animal pole, and short and thin (diameter 1.99 ± 0.23 μm, n = 20) adhesive filaments were around the long filaments. A micropyle was conical shaped with adhesive filament and located near the animal pole of egg. The outer surface of fertilized egg was rough side. Also, the total thickness of the fertilized egg envelope was about 7.46 ± 0.41 μm (n = 20), the fertilized egg envelope consisted of two layers, an inner lamellae layer and an outer layer with high electron-density. And the inner layer was 8 layers. Collectively, these morphological characteristics and adhesive property of fertilized egg with adhesive filaments, and ultrastructures of micropyle, outer surface, and section of fertilized egg envelope are showed species specificity.

中文翻译：

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从受精卵信封的超微结构Melanotaenia雷竹，Melanotaeniidae，真骨

我们用光学和电子显微镜检查了属于黑变种的矮虹鱼（Melanotaenia praecox）的受精卵的形态和受精卵的超微结构。受精卵是球形的，带有粘性细丝，透明，沉入水中，并具有狭窄的卵石空间和小的油滴。受精卵的大小为1.02±0.18 mm（n = 30），受精卵上有两种粘胶丝。长而粗（直径12.22±0.52μm，n = 20）的粘性长丝仅在动物杆的区域，而短而细（直径1.99±0.23μm，n = 20）的粘性长丝围绕着长纤维。微粒的圆锥形，带有粘性细丝，位于卵的动物杆附近。受精卵的外表面粗糙。还，受精卵壳的总厚度约为7.46±0.41μm（n = 20），受精卵壳由两层组成，内层薄层和外层具有高电子密度。内层为8层。总的来说，这些受精卵具有粘附细丝的形态学特征和粘附特性，以及受精卵包膜的超微结构，外表面和截面均显示出物种特异性。