ABSTRACT Spiders molt periodically before reaching full maturity, but several spiders continue to molt after sexual maturity. This post-maturity molting (PMM) behavior has been observed in the barn spider Araneus cavaticus (Araneae: Araneidae) among the orb-web spiders. In this study, we investigated molt-related changes in the ampulla and tail regions of the major ampullate gland during the PMM sequences (intermolt, pre-molt, ecdysis, and post-molt). The results showed that all gland units consist of a monolayer of epithelial cells surrounding a large central lumen, and two types of secretory granules (Type-M and Type-S). During the molting period, most cells showed fine structural modification in their organelles, and conspicuous tissue swelling was detected at the glandular epithelium. Following the molting cycle, the amount of Type-M granules continues to increase in the cell with a corresponding swelling, but Type-S granules gradually disappeared during the process of ecdysis. This suggests that the molt-related changes in spider silk production originates from the periodic production of Type-S secretory granules in the ampulla region. As Type-M granules flow toward the funnel, it is coated with viscous liquid secretion of Type-S granules in order to produce dragline silk fibers. We provide fine structural evidence for Type-S granules of hexagonal crystalline substructures representing glycoprotein substances to maintain high level of water content.

中文翻译：

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谷仓蜘蛛 Araneus cavaticus 主要壶状丝腺的蜕皮相关变化

摘要蜘蛛在完全成熟前会定期蜕皮，但有几只蜘蛛在性成熟后会继续蜕皮。这种成熟后蜕皮 (PMM) 行为已在圆网蜘蛛中的谷仓蜘蛛 Araneus cavaticus (Araneae: Araneidae) 中观察到。在这项研究中，我们调查了在 PMM 序列（换羽间、蜕皮前、蜕皮和蜕皮后）期间大壶腹腺壶腹和尾部区域的蜕皮相关变化。结果表明，所有腺体单位都由围绕大中央腔的单层上皮细胞和两种类型的分泌颗粒（M 型和 S 型）组成。在蜕皮期间，大多数细胞的细胞器显示出精细的结构改变，腺上皮组织明显肿胀。在蜕皮周期之后，M型颗粒在细胞内不断增多并相应膨胀，而S型颗粒在蜕皮过程中逐渐消失。这表明蜘蛛丝生产中与蜕皮相关的变化源于壶腹区域 S 型分泌颗粒的周期性产生。当 M 型颗粒流向漏斗时，它被 S 型颗粒的粘性液体分泌物包覆以产生拉丝纤维。我们为代表糖蛋白物质的六边形结晶亚结构的 S 型颗粒提供精细的结构证据，以保持高水平的水含量。这表明蜘蛛丝生产中与蜕皮相关的变化源于壶腹区域 S 型分泌颗粒的周期性产生。当 M 型颗粒流向漏斗时，它被 S 型颗粒的粘性液体分泌物包覆以产生拉丝纤维。我们为代表糖蛋白物质的六边形结晶亚结构的 S 型颗粒提供精细的结构证据，以保持高水平的水含量。这表明蜘蛛丝生产中与蜕皮相关的变化源于壶腹区域 S 型分泌颗粒的周期性产生。当 M 型颗粒流向漏斗时，它被 S 型颗粒的粘性液体分泌物包覆以产生拉丝纤维。我们为代表糖蛋白物质的六边形结晶亚结构的 S 型颗粒提供精细的结构证据，以保持高水平的水含量。