Development of the Ovary and the Female Reproductive Cells of the Lung Fluke, Paragonimus ohirai (Trematoda: Troglotrematidae)

Abstract

The ultrastructure of the ovary of Paragonimus ohirai was investigated in different developmental stages of experimental infection in rats, from the metacercarial stage to the adult stage. The female reproductive cells were observed in order to understand the development of the ovary. During its development in the definitive host, the ovarian primordium and the ovary increased in size and cell number and underwent morphological changes. The blind end of the female genitalia was an undifferentiated primordium at the metacercarial stage, but became the bud of an ovary on day 3. Germ cells and supporting cells were observed on day 5. Oogonia were identified in the 15-day-old ovary, followed by the appearance of young oocytes at 17 days. Large oocytes were found on day 19, but the 21-day-old ovary contained degenerated oocytes. Mature ovaries were observed in the 26-day-old worms and egg formation was seen to arise on day 28. The development of the ovary and female reproductive cells was discussed in relation to the physiology of P. ohirai.

An ultrastructural study of reproduction in the sporocysts of Prosorhynchoides gracilescens (Digenea: Bucephalidae)

“…In trematode adults, the nuage-like structures, referred to as "nucleoluslike cytoplasmic bodies," were recorded in oocytes of Fasciola hepatica (Gresson 1964), Gorgoderina attenuata (Koulish 1965), Pharyngostomoides procyonis (Grant et al 1977), and Prosthodendrium ascidia (Podvyaznaya 1990). In this connection, it is interesting to note the obvious similarity in the fine organization of the germinal masses described in the present study and the young ovaries observed by Orido (1987) in developing lung flukes Paragonimus ohirai. Both organs include supporting cells with a very similar morphology and also contain pycnotic bodies, which result from degeneration of germline cells.…”

Ultrastructural study of vitellogenesis and oogenesis ofCrepidostomum metoecus(Digenea, Allocreadiidae), intestinal parasite ofSalmo trutta(Pisces, Teleostei)

“…The initial phase of oocyte maturation takes place during the prophase of the first meiotic division in the ovary. As for Metadena depressa [14], no nucleus has been observed in the thin interstitial cytoplasmic layer between growing oocytes and the basal lamina, unlike in other Platyhelminthes where syncytial structures may occur in the ovary [34]. Oogonia are present along the wall of the ovary as for Cryptocotyle lingua [5], but do not contain a nucleolus-like Zygocotyle lunata [49].…”

Ultrastructure of the ovary, ovicapt and oviduct of the spathebothriidean tapeworm Didymobothrium rudolphii (Monticelli, 1890)

“…Oogenesis has been carefully studied in cestodes (Douglas 1963, Poddubnaya et al 2005b, flukes (Gresson 1964;Holy and Wittrock 1986;Orido 1987Orido , 1988 and monogeneans (Halton et al 1976, Tappenden et al 1993. Ultrastructural changes in the oocytes accompanying the initial phases of oogenesis in the ovary are basically the same in all platyhelminths, including those involving the oogonia, maturing oocytes and fully mature oocytes at different stages of their development.…”

“…Ultrastructural changes in the oocytes accompanying the initial phases of oogenesis in the ovary are basically the same in all platyhelminths, including those involving the oogonia, maturing oocytes and fully mature oocytes at different stages of their development. The ovarian interstitial tissue has a syncytial structure with several nuclei which may occur in any region of the ovary in spathebothriidean tapeworms (Poddubnaya et al 2005b) and in lung flukes (Orido 1987). Oocyte inclusions of the Spathebothriidea are cortical granules and a few lipid droplets.…”