Hüttemann Maria, Schmahl Günter, Mehlhorn Heinz
Institute of Zoomorphology, Cellbiology and Parasitology, Heinrich-Heine-University Düsseldorf, Universitätsstrasse 1, 40225, Düsseldorf, Germany.
Parasitol Res. 2007 Sep;101 Suppl 2:S225-32. doi: 10.1007/s00436-007-0698-1.
The morphological characteristics of the adult heteroxenous blood nematode Angiostrongylus cantonensis and the adult monoxenous intestinal nematode Trichuris muris were compared with special regard to the ultrastructure of their digestive systems. The small circular mouth of A. cantonensis appears sucker like. The very narrow mouth of T. muris is surrounded by three lips covered by the cuticle that extends into the buccal space. In the buccal cavity of A. cantonensis, a single tooth occurs opposite to a cutting plate, while no teeth are present in T. muris. The lumen of the well-developed muscular pharynx of A. cantonensis shows a trifurcated star-like cross-section. The anterior segment of the bipartite pharynx presumably functions as a pump. The lumen of the bipartite pharynx and esophagus of T. muris exhibits a very narrow oval cross-section and possesses no musculature. It is composed of a long column of stichosome cells. The esophagus region is lined inside by bands of bacillary cells as well as outside by two longitudinal rows of funnel-like papillae. These structures may be involved in the uptake of nutrients by T. muris. The gland cells might excrete digestive exoenzymes, while the bacillary cells take up the predigested nutrients. The presence of many vesicles suggests a vesicular transport of the material into the pharynx. The intestinal epithelium of A. cantonensis is densely covered with short microvilli. The lumen itself is filled with red blood cells originating from host blood. The intestine of T. muris has a thick epithelium being placed on a basal lamina and shows long thin microvilli. The intestinal lumen is very narrow and free from particles or granules. This again suggests that T. muris lives on low molecular nutrients resorbed from the environment. The epithelium cells of the intestine of T. muris contain glycogen and electron light granules but are lacking mitochondria. This finding may indicate that the epithelium cells have an anaerobic energy metabolism. This statement fits with the fact that the habitat of the worm, the cecum, is largely anaerobic.
对成年异宿主血液线虫广州管圆线虫和成年单宿主肠道线虫鼠鞭虫的形态特征进行了比较，特别关注了它们消化系统的超微结构。广州管圆线虫的小圆形口呈吸盘状。鼠鞭虫非常狭窄的口被三层由角质层覆盖的唇包围，角质层延伸至口腔空间。在广州管圆线虫的口腔中，有一颗牙齿与一个切割板相对，而鼠鞭虫没有牙齿。广州管圆线虫发育良好的肌肉咽腔呈现出三叉星状横截面。二分咽的前段可能起到泵的作用。鼠鞭虫二分咽和食管的腔呈现出非常狭窄的椭圆形横截面，且没有肌肉组织。它由一长列刺细胞组成。食管区域内部由杆菌细胞带排列，外部由两排纵向的漏斗状乳头排列。这些结构可能参与了鼠鞭虫对营养物质的摄取。腺细胞可能分泌消化外酶，而杆菌细胞摄取预先消化的营养物质。许多小泡的存在表明物质通过小泡运输到咽部。广州管圆线虫的肠上皮密布着短微绒毛。肠腔本身充满了来自宿主血液的红细胞。鼠鞭虫的肠道有一层厚上皮，位于基膜上，有长而细的微绒毛。肠腔非常狭窄，没有颗粒或微粒。这再次表明鼠鞭虫以从环境中吸收的低分子营养物质为生。鼠鞭虫肠道的上皮细胞含有糖原和电子透明颗粒，但没有线粒体。这一发现可能表明上皮细胞具有无氧能量代谢。这一说法与该蠕虫的栖息地盲肠在很大程度上是无氧的这一事实相符。
