Figure 3.

The egg envelope ultrastructure of six representative species with semibuoyant eggs (C. alburnus-B, H. molitrix, H. nobilis, C. idella, M. piceus, and S. curriculus) and three representative species with adhesive eggs (C. alburnus-A, M. amblycephala, and C. dabryi) of endemic East Asian cyprinids. (a) TEM images of the egg envelopes of unfertilized eggs (scale bar is 10 μm). EE: egg envelope. (b) TEM images of the egg envelopes of unfertilized eggs (scale bar is 500 nm). The egg envelopes of semibuoyant eggs were divided into three layers (1, 2, and 3), and the egg envelopes of adhesive eggs were divided into four layers (1, 2, 3, and 4). (c) TEM images of the adhesive layer of eggs at 1 h post fertilization (scale bar is 2 μm). AL: adhesive layer; BE: semibuoyant egg; AE: adhesive egg.