Martínez Claudio, Paredes R, Stock R P, Saralegui A, Andreu M, Cabezón C, Ehrlich R, Galanti N
Sección Bioquímica, Facultad de Ciencias, Universidad de la República, Iguá 4225, CP1400, Montevideo, Uruguay.
J Cell Biochem. 2005 Feb 1;94(2):327-35. doi: 10.1002/jcb.20294.
Echinococcus granulosus is the causative agent of hydatidosis, a major zoonoses that affects humans and herbivorous domestic animals. The disease is caused by the pressure exerted on viscera by hydatid cysts that are formed upon ingestion of E. granulosus eggs excreted by canine. Protoscoleces, larval forms infective to canine, develop asynchronously and clonally from the germinal layer (GL) of hydatid cysts. In this report, we describe the cellular organization and the appearance of differentiated structures both in nascent buds and developed protoscoleces attached to the GL. Early protoscolex morphogenesis is a highly complex and dynamic process starting from the constitution of a foramen in the early bud, around which nuclei are distributed mainly at the lateral and apical regions. Similarly, distribution of nuclei in mature protoscoleces is not homogenous but underlies three cellular territories: the suckers, the rostellar pad, and the body, that surrounds the foramen. Several nuclei are associated to calcareous corpuscles (Cc), differentiated structures that are absent in the earlier bud stages. The number of nuclei is similar from the grown, elongated bud stage to the mature protoscolex attached to the GL, strongly suggesting that there is no significant cellular proliferation during final protoscolex development. The amount of DNA per nucleus is in the same range to the one described for most other platyhelminthes. Our results point to a sequential series of events involving cell proliferation, spatial cell organization, and differentiation, starting in early buds at the GL of fertile hydatid cysts leading to mature protoscoleces infective to canine.
细粒棘球绦虫是包虫病的病原体，包虫病是一种影响人类和草食性家畜的主要人畜共患病。该疾病是由于摄入犬排出的细粒棘球绦虫虫卵后形成的包虫囊肿对内脏施加压力所致。原头节是对犬有感染性的幼虫形式，从包虫囊肿的生发层（GL）异步克隆发育而来。在本报告中，我们描述了新生芽和附着在GL上发育成熟的原头节中的细胞组织和分化结构的外观。早期原头节形态发生是一个高度复杂且动态的过程，始于早期芽中孔的形成，细胞核主要分布在孔的侧面和顶端区域。同样，成熟原头节中的细胞核分布也不均匀，而是位于三个细胞区域：吸盘、顶突垫和围绕孔的身体部分。一些细胞核与钙质小体（Cc）相关联，钙质小体是早期芽阶段不存在的分化结构。从生长的细长芽阶段到附着在GL上的成熟原头节，细胞核数量相似，这强烈表明在原头节最终发育过程中没有明显的细胞增殖。每个细胞核的DNA量与大多数其他扁形动物所描述的范围相同。我们的结果表明，一系列连续事件涉及细胞增殖、空间细胞组织和分化，始于肥沃包虫囊肿GL处的早期芽，最终形成对犬有感染性的成熟原头节。
