家蚕茧和蓖麻蚕茧不同茧层的茧丝形态结构分析

An Analysis on Morphological Structure of Cocoon Filaments from Diffrerent Layers of Mulberry Silkworm and Eri-silkworm Cocoons

茧层的茧丝形态结构特点是研究不同种类茧丝纤维的形成与蚕吐丝生理过程及制定原料茧加工工艺技术的重要依据之一。采用光学显微镜观察家蚕茧与蓖麻蚕茧的茧衣和外、中、内茧层茧丝的横截面形貌特征,利用显微粒度分析软件测量茧丝长径、短径、截面积,得到不同茧层茧丝扁平度、圆整度等表征指标的变化趋势:家蚕茧和蓖麻蚕茧茧丝的所有形态结构表征指标变异系数的变化趋势均表现为茧衣最大,外层次之,中层最小;茧丝扁平度与圆整度均是从外层到中层达到顶峰后至内层又逐渐减小,但家蚕茧茧衣的茧丝圆整度较小,而蓖麻蚕茧茧衣的茧丝圆整度较大;家蚕茧茧丝的截面积在中层最大,故中层茧层茧丝最饱满,而蓖麻蚕茧茧丝的截面积从外层到内层逐渐减小。采用原子力显微镜观察蓖麻蚕茧茧丝横截面的三维形貌,可见其茧丝中心部位结构比较疏松,推测可能是由于聚集态结构差异造成的。此外,蓖麻蚕茧茧丝纵向表面不同程度粘附有结晶物,而家蚕茧茧丝纵向表面光滑。

The characteristics of morphological structure of cocoon filaments from cocoon layers are important references for studying the formation of different types of cocoon filament fibers and the physiological process of larva spinning and for selecting appropriate technology to process the raw cocoons. The cross-section structure of cocoon floss and cocoon filaments from the outer, middle and inner layers of cocoon shell of both mulberry silkworm and ersilkworm was ob- served under optical microscope. The major axis, minor axis and cross-sectional area were measured with the help of microscopic granularity analysis software, so as to obtain variation tendency of the compressed degree and roundness of cocoon filaments from different layers. It was found that cocoon floss of both mulberry silkworm and eri-silkworm had the highest variation coefficients in all characterized indexes on morphological structures while the outer layer ranked the second and the middle layer had the least variation coefficients. Both the compressed degree and roundness increased from the outer layer to the middle layer at which peak value was achieved and then decreased towards the inner layer. The roundness of cocoon filament from mullberry silkworm cocoon floss was relatively lower than that of eri-silkworm cocoon floss. Mulberry silkworm cocoon filament had the largest cross-sectional area at middle layer and thus its middle layer was well-formed. On the other hand, the cross-sectional area of eri-silkworm cocoon filament decreased gradually from the outer layer to the inner layer. Observation with atomic force microscope to three dimensional morphology revealed that the cross-section of eri-silkworm cocoon filament was loose at the center, which could be resulted from difference of aggregation structure. Besides, there were certain number of crystals on the surface of eri-silkworm cocoon filament, while the surface of mulberry silkworm cocoon filament was smooth.