Abnormal Spermatogenesis in the Common Liver Fluke (Fasciola sp.) from Japan and Korea.

Abstract

ABSTRACT. Diploid and triploid specimens of Japanese and Korean Fasciola sp. showed abnormality in their spermatogenesis. Live germ cells obtained from the testes were observed under a differential interference contrast microscope. In the stages from spermatogonium to spermatid, the cells combined together at the central cytoplasmic bridge during a series of divisions. One spermatogonium becomes a cell group of 8 primary spermatocytes through 3 mitoses. Until the primary spermatocyte stage, cells are divided in a uniform manner. In most of the diploid specimens, the primary spermatocytes are irregularly divided into non-uniform secondary spermatocytes, however, some specimens perform a regular division. In the majority of triploid flukes, the primary spermatocytes are divided in a regular pattern, but some of the specimens perform an irregular division. The non-uniform spermatids do not perform a spermiogenesis. In the diploid specimens, no spermatozoa were found that were produced by spermiogenesis. Whereas in the triploid specimens, some spermatids distributed uniformly on the surface went through a spermiogenesis. We observed some moving spermatozoa in one triploid specimen. The spermatozoa possibly retain their normal reproductive function. -KEY WORDS: chromosome, Fasciola, parthenogenesis, spermatogenesis, triploid.

Molecular characterization of Fasciola hepatica, Fasciola gigantica, and aspermic Fasciola sp. in China based on nuclear and mitochondrial DNA

“…These intermediate forms are difficult to identify accurately. Moreover, Asian Fasciola forms include aspermic diploid and triploid specimens that are meiotically dysfunctional and gynogenic (Moriyama et al 1979;Sakaguchi 1980;Terasaki et al 1998). Aspermic specimens from Japan, Korea, and Vietnam exhibited heterogeneity between F. hepatica and F. gigantica in nuclear ribosomal and mitochondrial DNA, suggesting that their origin may be hybridyzation between the two species (Itagaki and Tsutsumi 1998;Agatsuma et al 2000;Itagaki et al 2005a, b;Itagaki et al 2009).…”

Molecular Analysis of Aspermic <i>Fasciola</i> Flukes from Korea on the Basis of the Nuclear ITS1 Region and Mitochondrial DNA Markers and Comparison with Japanese Aspermic <i>Fasciola</i> Flukes

“…Particularly in the former 2 countries, all of the Fasciola flukes analyzed were aspermic [7,10,12,18]. Accurate species identification of aspermic Fasciola flukes remains uncertain, not only because they display intermediate morphological features of F. hepatica and F. gigantica but also because they possess no or only a few sperm in their seminal vesicles.…”

“…Accurate species identification of aspermic Fasciola flukes remains uncertain, not only because they display intermediate morphological features of F. hepatica and F. gigantica but also because they possess no or only a few sperm in their seminal vesicles. It has been revealed that aspermic Fasciola flukes have a meiotic disorder affecting spermatogenesis [18], which suggests that they are parthenogenetic.…”

A description of karyotype of the giant liver fluke Fascioloides magna (Trematoda, Platyhelminthes) and a review of Fasciolidae cytogenetics

“…exhibit not only diploid, but also triploid populations and even mixoploid (2n/3n) specimens (e.g. Moriyama et al, 1979;Sakaguchi, 1980;Terasaki et al, 1998Terasaki et al, , 2000Itagaki et al, 2009;Srimuzipo et al, 2000;Ichikawa & Itagaki, 2010). Additionally, triploid F. hepatica has been found in Britain and Ireland (Fletcher et al, 2004).…”