Ultrastructure of the female gonad of two temnocephalids (Platyhelminthes,Rhabdocoela)

The female gonad of Temnocephala dendyi and T: minor consists of a single g ermarium and two rows of vitellaria. It is enveloped by an extracellular la mina and accessory cells. Accessory cells are only peripherally located in the germarium while their cytoplasmic projections also fill the spaces betw een vitellocytes in the vitellarium. The main feature of oocyte maturation is the appearance of chromatoid bodies and the development of rough endopla smic reticulum (R.E.R.) and Golgi complexes which appear to be correlated w ith the production of double-structured egg granules. The egg granules, whi ch are localized in the cortical cytoplasm of mature oocytes, contain glyco proteins, are devoid of polyphenols and are similar in structure and compos ition to the cortical granules observed in some Digenea and Monogenea. Vite llocytes are typical secretory cells with well-developed R.E.R. and Golgi c omplexes which are involved in the production of shell globules and yolk. T he multigranular pattern and the polyphenolic composition of the shell glob ules of the temnocephalids investigated are similar to those observed in ot her rhabdocoels, and in some Prolecithophora and Neodermata. This feature m ay represent a synapomorphy shared by these taxa.