Laboratori de Parasitologia, Departament de Microbiologia i Parasitologia Sanitàries, Facultat de Farmàcia, Universitat de Barcelona, Av. Joan XXIII, sn, E08028, Barcelona, Spain.
Parasitol Res. 2012 Jan;110(1):19-30. doi: 10.1007/s00436-011-2446-9. Epub 2011 May 17.
Spermiogenesis and the ultrastructure of the spermatozoon of the bothriocephalidean cestode Clestobothrium crassiceps (Rudolphi, 1819), a parasite of the teleost fish Merluccius merluccius (Linnaeus, 1758), have been studied by means of transmission electron microscopy. Spermiogenesis involves firstly the formation of a differentiation zone. It is characterized by the presence of two centrioles associated with striated rootlets, an intercentriolar body and an electron-dense material in the apical region of this zone. Later, two flagella develop from the centrioles, growing orthogonally in relation to the median cytoplasmic process. Flagella then undergo a rotation of 90° until they become parallel to the median cytoplasmic process, followed by the proximodistal fusion of the flagella with the median cytoplasmic process. The nucleus elongates and afterwards it migrates along the spermatid body. Spermiogenesis finishes with the appearance of the apical cone surrounded by the single helical crested body at the base of the spermatid. Finally, the narrowing of the ring of arched membranes detaches the fully formed spermatozoon. The mature spermatozoon of C. crassiceps is filiform and contains two axonemes of the 9 + "1" trepaxonematan pattern, a parallel nucleus, parallel cortical microtubules, and electron-dense granules of glycogen. The anterior extremity of the gamete exhibits a short electron-dense apical cone and one crested body, which turns once around the sperm cell. The first axoneme is surrounded by a ring of thick cortical microtubules that persist until the appearance of the second axoneme. Later, these thick cortical microtubules disappear and thus, the mature spermatozoon exhibits two bundles of thin cortical microtubules. The posterior extremity of the male gamete presents only the nucleus. Results are discussed and compared particularly with the available ultrastructural data on the former "pseudophyllideans". Two differences can be established between spermatozoa of Bothriocephalidea and Diphyllobothriidea, the type of spermatozoon (II vs I) and the presence/absence of the ring of cortical microtubules.
采用透射电子显微镜研究了鱼类绦虫 Clestobothrium crassiceps（Rudolphi，1819）的精子发生和精子超微结构。精子发生首先涉及到分化区的形成。其特征是存在两个与纹状根相连的中心粒、中心粒间体和在该区域顶端的电子致密物质。随后，两个鞭毛从中心粒发育而来，与中央细胞质突起成直角生长。鞭毛随后旋转 90°，直到它们与中央细胞质突起平行，随后鞭毛与中央细胞质突起的近-远侧融合。核伸长，随后沿着精细胞体迁移。精子发生完成时，在精细胞底部出现由单个螺旋顶体围绕的顶端圆锥体。最后，拱形膜环的变窄使完全形成的精子脱落。C. crassiceps 的成熟精子呈丝状，包含 9+“1”的 trepaxonematan 模式的两个轴丝、平行核、平行皮质微管和电子致密的糖原颗粒。配子的前端有一个短的电子致密的顶端圆锥体和一个顶体，它在精子细胞周围旋转一次。第一个轴丝被一层厚的皮质微管环绕，直到第二个轴丝出现。随后，这些厚的皮质微管消失，因此成熟的精子显示出两个薄的皮质微管束。雄性配子的后端只有核。结果进行了讨论，并特别与以前的“假叶目”的可用超微结构数据进行了比较。可以在绦虫目和双叶目之间建立两个区别，即精子类型（II 型与 I 型）和皮质微管环的存在/不存在。
