Abstract: The parthenogenetic egg (PE) is centrolecithal and its embryogenesis lasts about 45 hours at 24 ℃. According to the morphological and histological changes, the embryonic development of D. carinata could be divided into seven major stages, i.e. the cleavage stage, blastula stage, gastrula stage, eggnauplius stage, eggmetanauplius stage, embryo with eye pigments, and preparehatchling stage. The superficial cleavage of PE did not happen until approximately 40 minutes after egg laying. At the end of cleavage, the embryo consisted of 256 cells and reached the blastula stage at which a large part of the blastocoele was filled with yolk granules, accompanying by the formation of a thin sheet of divided cells. The cell division rate was accelerated and gastrulation took place by means of immigration of blastodermal cells at the end of this stage. Afterwards, the morphological changes in embryo development became remarkable. The eggnauplius stage was characterized by the appearance of the rudiments of two antennae and a mandible in the head region of the embryo, while the eggmetanauplius stage characterized by the formation of the thoracic segments, thoracic limbs, carpace, and guts. At the eye pigments stage, the embryo was found presenting the eye pigmentation in the welldeveloped compound eyes. Simultaneously, other physiologically important tissues and organs started to develop. During the last preparehatching stage, the organelle structure in the embryo could be quite similar to that in the larval. The results could accumulate basic biological information for further research on embryonic development of Cladocera.

Key words: embryonic development, morphology, Daphnia carinata, embryonic development, morphology