[Embryonic development of Taenia pisiformis and T. hydatigena (Cestoidea, Cyclophyllidea)]

A description of the consecutive stages of ripening of ovary cells of early fission and gastrulation of T. pisiformis and T. hydatigena, peculiar to the common type of fission of Cyclophyllidea is given. The fission has signs of double spiral fission which takes place in primitive Turbellaria. The primitiveness of early embryogenesis is reflected in early determination of macromeres, in the absence of strict regulation in the location of blastomeres, in the formation of blastula and unipolar gastrulation with the absence of morphological differentiation of ectoderm and mesenchyme.