Papassideri I S, Margaritis L H
Department of Biology, University of Athens, Panepistimiopolis, Greece.
Tissue Cell. 1996 Aug;28(4):401-9. doi: 10.1016/s0040-8166(96)80026-7.
Synthesis and morphogenesis of the innermost chorionic layer (ICL) was investigated by conventional EM methods, freeze-fracturing, tissue culture in Robb's medium, and EM autoradiography. Both autoradiography and fine structure results have shown that ICL-components are secreted prior to other chorion proteins. Their secretion starts on stage 12a but the first layer of ICL molecules is visible at stage 12b. Its thickness is gradually increased during the next stages, taking first, a bilaminar form along with the inner endochorion. Later, at the end of choriogenesis, ICL is detached from the endochorion and takes its final thickness and configuration, consisting of a 3-dimensional crystal, about 40 nm thick. The isolated ICL in conditions of air water interface is a monolayer crystal 10 nm thick. Studies on chorion mutants showed that the amount of protein secreted by the follicle cells is independent to the process of crystallisation. These data show how a proteinaceous extracellular substance is gradually assembled to form a 3-D crystal and how it can be organised to perform functions such as the physiological resistance of the insect eggs against water loss or water uptake, whenever they are laid on substrates with extreme environmental conditions. These functions are performed by ICL in conjunction with the underlying wax layer.
采用传统电子显微镜方法、冷冻断裂技术、在罗布培养基中进行组织培养以及电子显微镜放射自显影术，对最内层绒毛膜层（ICL）的合成与形态发生进行了研究。放射自显影和精细结构研究结果均表明，ICL成分比其他绒毛膜蛋白分泌得更早。它们在12a期开始分泌，但在12b期才可见到ICL分子的第一层。在接下来的阶段，其厚度逐渐增加，首先与内绒毛膜一起形成双层结构。后来，在绒毛膜形成末期，ICL与绒毛膜分离，并达到其最终厚度和形态，由一个约40纳米厚的三维晶体组成。在空气 - 水界面条件下分离出的ICL是一个10纳米厚的单层晶体。对绒毛膜突变体的研究表明，卵泡细胞分泌的蛋白质量与结晶过程无关。这些数据展示了一种蛋白质类细胞外物质是如何逐渐组装形成三维晶体的，以及它如何被组织起来发挥功能，比如当昆虫卵产在具有极端环境条件的基质上时，它能起到昆虫卵防止水分流失或吸收水分的生理抗性作用。这些功能是由ICL与下面的蜡层共同完成的。
