Margaritis L H, Kafatos F C, Petri W H
J Cell Sci. 1980 Jun;43:1-35. doi: 10.1242/jcs.43.1.1.
The fine structure of the several layers and regional specializations in the Drosophila melanogaster eggshell has been studied by a combination of shell isolation procedures and ultrastructural techniques (conventional TEM, whole-mount TEM, SEM, HVEM, freeze-fracture electron microscopy utilizing rotary replication, shadow casting, optical diffraction and stereo imaging). The main shell consists of 5 layers: the vitelline membrane (300 nm thick), the wax layer, the innermost chorionic layer (40-50 nm), the endochorion (500-700 nm), and the exochorion (300-500 nm). The vitelline membrane consists of irregularly organized particles. The wax layer appears to contain multilayered hydrophobic plates which split tangenitally upon freeze fracturing. The innermost chorionic layer is composed of a crystalling lattice. The endochorion is made of a thin (40 nm) fenestrated floor composed of 40-nm fibres and an outer solid (200 nm) roof covered with a network of 40-nm strands. Intermittently spaced pillar connect these 2 parts. Similarities in the substructure of the floor, pillars and roof suggest that they may be composed of similar or identical structural elements. The specialized regions of the shell are the 2 respiratory appendages, the operculum area and the posterior pole. The appendages exhibit 2 sharply distinct surfaces, a dorsal side with isolated 1.5-micrometer plaques and a ventral side with strands of 40-50 nm connected in a network with openings of 70-80 nm. The operculum area, which includes the micropoyle and the collar, is distinguished by 3 unique types of cell imprints. The posterior pole contains 2 distinctive populations of cell imprints: the central area has very thin intercellular ridges and a thin, perforated, endochorionic roof, while the peripheral area contains mixed, thick and thin, intercellular ridges and serves as a transition zone to the main shell pattern. The pillars in the central area of the posterior pole have a distinct arrangement, forming one peripheral circle within each cell imprint. An analysis utilizing structural and developmental criteria indicates that as many as ten different populations of follicular epithelial cells may be involved in the construction of the various regions of the Drosophila eggshell.
通过蛋壳分离程序和超微结构技术（传统透射电子显微镜、整装透射电子显微镜、扫描电子显微镜、高压电子显微镜、利用旋转复制、投影、光学衍射和立体成像的冷冻断裂电子显微镜）相结合的方法，对黑腹果蝇卵壳各层的精细结构和区域特化进行了研究。主要的卵壳由5层组成：卵黄膜（厚300纳米）、蜡层、最内层的绒毛膜层（40 - 50纳米）、内膜（500 - 700纳米）和外膜（300 - 500纳米）。卵黄膜由不规则排列的颗粒组成。蜡层似乎包含多层疏水板，在冷冻断裂时沿切线方向分裂。最内层的绒毛膜层由晶格组成。内膜由一层薄的（40纳米）有孔底板和一个覆盖着40纳米链网络的外部固体（200纳米）顶板组成，底板由40纳米的纤维构成。间隔排列的柱状结构连接这两个部分。底板、柱状结构和顶板的亚结构相似性表明它们可能由相似或相同的结构元件组成。卵壳的特化区域是两个呼吸附属物、卵盖区域和后极。附属物呈现出两个截然不同的表面，一个背侧有孤立的1.5微米斑块，一个腹侧有40 - 50纳米的链，这些链相互连接形成一个有70 - 80纳米开口的网络。卵盖区域包括微孔和颈环，其特征是有3种独特类型的细胞印记。后极包含两种不同类型的细胞印记群体：中心区域有非常薄的细胞间嵴和一个薄的、有孔的内膜顶板，而周边区域包含混合的、厚的和薄的细胞间嵴，并且作为向主要卵壳模式的过渡区域。后极中心区域的柱状结构有独特的排列方式，在每个细胞印记内形成一个周边圆圈。利用结构和发育标准进行的分析表明，多达十种不同群体的卵泡上皮细胞可能参与了黑腹果蝇卵壳各个区域的构建。
