Ultrastructural Studies on Spermatogenesis in a Parthenogenetic Type of Paragonimus westermani (Kerbert 1878) Proposed as P. pulmonalis (Baelz 1880)

Abstract

Spermatogenesis in a parthenogenetic type of P. westermani (Kerbert 1878) called P. pulmonalis (Baelz 1880) throughout this study, was observed by light microscopy (LM), scanning (SEM), and transmission (TEM) electron microscopy. During spermatogenesis, most of the cells became degenerated or malformed as a result of aberrations during spermatogenesis. Vacuolated cells were often found in the testicular lumen. In some nuclei of spermatocytes, synaptonemal complexes were formed and this indicated that some pairing of homologous chromosomes did occur, but only rarely. Cytophores in some rosettes were broken down into small fragments and the cells separated from each other. Norman spermatozoa were very rarely found in the testis and never in the seminal receptacle, where egg and vitelline cells were present instead. Throughout spermatogenesis, Golgi complexes, mitochondria, ribosomes, and endoplasmic reticulum were not abundant, and this suggested that cell activities and protein synthesis were greatly reduced.

Vitellogenesis in the cestode Atractolytocestus huronensis Anthony, 1958 (Caryophyllidea: Lytocestidae)

“…Parthenogenesis has been reported on the basis of chromosomal analyses in two other cestodes (Glaridacris catostomi (only in an isolated population of Catostomus commersoni) by Grey and Mackiewicz (1980) and Diphyllobothrium erinacei by Sasada (1978)) and three trematodes (Bunodera sacculata by Cannon (1971), Fasciola sp. by Sakaguchi and Nakagawa (1975), Sakaguchi and Yoneda (1976), and Paragonimus pulmonalis by Fujino and Ishii (1982)). No data are available on vitellogenesis in the parthenogenetic cestode species.…”

Ultrastructural aspects of spermatogenesis, testes, and vas deferens in the parthenogenetic tapeworm Atractolytocestus huronensis Anthony, 1958 (Cestoda: Caryophyllidea), a carp parasite from Slovakia

“…The nuclei of the secondary spermatocytes of A. huronensis are subdivided into two or more isolated fragments, indicating aberrant meiosis. The two or more nuclei at different developing stages were found in each single spermatid in P. pulmonalis (Fujino and Ishii 1982). The formation of syncytial structures in testes of P. pulmonalis coincides strongly with the multinucleated profiles occurring in European A. huronensis.…”

“…Spermatogonial divisions in both European and American specimens show the features of normal mitosis and produce primary spermatocytes. In addition, the present study has determined the occurrence of some pairing of homologous chromosomes in the nuclei of primary spermatocytes of A. huronensis, which indicates an ongoing prophase of the first meiotic division in most sexually reproducing organisms (von Wettstein 1977;von Wettstein et al 1984;Dobson et al 1994), including trematodes and cestodes with either normal or parthenogenetic reproduction (Fujino and Ishii 1982;Halton and Hardcastle 1976;Robinson and Bogitsch 1978; the present study).…”

“…The literature on parthenogenesis in trematodes includes reports of Cannon (1971), Sakaguchi and Nakagawa (1975), Sakaguchi and Yoneda (1976), and Jourdane et al (1995). Ultrastructural observations on spermatogenesis in the parthenogenetic digeneans are not extensive and are restricted to one species only, Paragonimus pulmonalis by Fujino and Ishii (1982).…”

Paragonimiasis

“…However, in NE China, Japan, and Korea, triploid worms are common and often sympatric with diploids [ 87 ]. Triploids are unable to produce normal sperm [ 88 ]. However, they do produce eggs parthenogenetically.…”