Oogenesis in three species of Naidinae (Annelida, Clitellata) is extraovarian of the Stylaria type

Description of ovary organization and oogenesis in a phreodrilid clitellate

“…Naidadae is a large group of microdriles and according to Erséus, Wetzel & Gustavsson () and Erséus et al () Naididae unites eight subfamilies: Naidinae Ehrenberg, 1828; Pristininae Lastočkin, 1921; Opistocystinae Černosvitov, 1936; Tubificinae, Telmatodrilinae Eisen, 1879; Rhyacodrilinae Hrabě, 1963; Phallodrilinae Brinkhurst, 1971; and Limnodriloidinae Erséus, 1982. Among these subfamilies ovary organization and oogenesis are well known in Naidinae (Gorgoń et al, ), Tubificinae (Urbisz et al, , ) and Limnodriloidinae (Urbisz et al, ) and, as highlighted above, the characters connected with female germ‐line cyst organization and functioning found in I. biffidus are most similar to those observed in Naidinae, but differ substantially form Tubificinae and Limnodriloidinae. The organization of female germ‐line cyst found in Enchytraeidae is also similar to the phreodrilid studied.…”

“…We summarize that Insulodrilus bifidus possess female germ‐line cysts of the same composition and form as others clitellate annelids, that is, each germ line cell has one RC connecting it with the central cytophore and the fate of interconnected cell are different, that is, the majority function as NCs and only one or sometimes more become oocytes. To date, germline cysts have been described in numerous clitellates, including several families of leeches including Glossiphoniidae (Aisenstadt, ; Damas, ; Świątek, ), Hirudinidae and Haemopidae (Świątek, ; Ben Ahmed, Fuchs, Tekaya, Harrath & Świątek, ), Erpobdellidae (Świątek, Krok & Bielecki, ) and Salifidae (Urbisz, Lai, & Świątek, ) and microdrile taxa such as Lumbriculidae (Urbisz & Świątek, ), Tubificinae (Urbisz, Krodkiewska & Świątek, ; Urbisz, Chajec & Świątek, ), Limnodriloidinae (Urbisz, Chajec, Ito & Ito, ), Enchytraeidae (Paschma, ; Dumont, ; Urbisz et al, ), Naidinae (Gorgoń, Wardas, Krodkiewska & Świątek, ) and Propappidae (Gorgoń, Krodkiewska & Świątek, ). Moreover, cysts equipped with a cytophore have been noticed in such earthworms as Eisenia foetida (Chapron & Relexans, ) and Dendrobaena veneta (Siekierska, ).…”

“…As oogenesis progresses, cysts with a vitellogenic oocyte can detach from ovaries and oogenesis is completed in the segment cavity (Figure b; Urbisz et al, ; Świątek et al, ). On the other hand, in Naidinae 28 to 32 cells are joined into spherical cysts (Dehorne, ; Gorgoń et al, ). In Stylaria lacustris , Ripistes parasita and Chaetogaster diaphanus cysts function mainly in the body cavity, where the interconnected germ cells differentiate into about 30 NCs and one growing oocyte (Gorgoń et al, ).…”

“…On the other hand, in Naidinae 28 to 32 cells are joined into spherical cysts (Dehorne, ; Gorgoń et al, ). In Stylaria lacustris , Ripistes parasita and Chaetogaster diaphanus cysts function mainly in the body cavity, where the interconnected germ cells differentiate into about 30 NCs and one growing oocyte (Gorgoń et al, ). The ovaries of the studied naidines are small and contain cysts uniting oogonia and cells entering meiosis only.…”

“…The ovaries of the studied naidines are small and contain cysts uniting oogonia and cells entering meiosis only. The diversification of cell fate and yolk absorption by an oocyte occur outside the gonad so this kind of oogenesis can be termed as extraovarian (Figure c; Gorgoń et al, ). The cysts characteristic for Naidinae were termed as “Stylaria” cysts (Gorgoń et al, ).…”