Smith S A, Richards K S
Department of Biological Sciences, University of Keele, Staffs, UK.
Parasitology. 1991 Oct;103 Pt 2:267-74. doi: 10.1017/s0031182000059540.
The rostellar distal cytoplasm of Echinococcus granulosus protoscoleces is characterized by extensive basal membrane infolding, prominent hemidesmosomes and is subtended by a lamina reticularis with microfibrils of approximately 10 nm diameter that occasionally show a 55 nm banding periodicity. The rostellar hooks, in 2 rows, each have a blade, guard and handle region and possess a central amorphous pulp, a middle microfibrillar medulla with microfibrils of approximately 4 nm diameter, and a complex outer cortex in all but the proximal region of the guard and the base of the handle. In these regions additional material, of similar electron density to the medulla, but lacking the fibrillar substructure, occurs and gives the areas a lobed appearance. Energy-dispersive X-ray microanalysis of whole hooks demonstrated the presence of sulphur and trace quantities of phosphorus. X-ray near-edge absorption spectra resembled those of cystine, feather and hair and showed the sulphur to be predominantly in the form of disulphide linkages. X-ray diffraction patterns of whole hook preparations revealed 2 diffuse rings with equatorial spacings of 7.99 A and 15.22 A, thus differing from vertebrate keratins.
细粒棘球绦虫原头节的顶突远端细胞质的特征为基底膜广泛内褶、显著的半桥粒，并由直径约10 nm的微原纤维组成的网状板支撑，这些微原纤维偶尔显示出55 nm的带状周期性。顶突小钩排成2排，每一个都有刃、护膜和柄部区域，并且除了护膜近端区域和柄基部外，均具有中央无定形髓质、直径约4 nm的中间微原纤维髓质以及复杂的外部皮质。在这些区域中，出现了与髓质电子密度相似但缺乏纤维亚结构的额外物质，使这些区域呈现出叶状外观。对整个小钩进行能量色散X射线微分析表明存在硫和痕量的磷。X射线近边吸收光谱类似于胱氨酸、羽毛和毛发的光谱，显示硫主要以二硫键的形式存在。整个小钩制剂的X射线衍射图谱显示有2个漫射环，赤道间距分别为7.99 Å和15.22 Å，因此与脊椎动物角蛋白不同。
