Fig. 3

A Prochilodus magdalenae, developmental cleavage period from (A) 2C: 2-cell; (B) 4C: 4-cell; (C) 8C: 8-cell; (D) 16C: 16-cell; (E) 32C: 32-cell to (F) 64C: 64-cell. B Prochilodus magdalenae, developmental cleavage period from (A) 4C: 4-cell with the animal pole showing an incomplete division; the cells are dome-shaped and become increasingly convex toward the vitelline membrane, H&E 4X; (B) 8C: 8-cell, the blastodisc is characterized to be a clear, yolk-free region located at the animal pole. The vitellus occupies 75% of the surface area composed of circular and pleomorphic eosinophilic proteinaceous particles with different sizes, H&E 4X; (C) 16C: 16-cell. The cells have a domed shape with a convex surface, some of them being in the process of active cell division, H&E 40X. Abbreviations: AP: animal pole; B: blastodisc; CD: active cell division; YG: yolk granules